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Albert M. Chang

Professor of Physics
Physics
Box 90305, Durham, NC 27708
Rm: 091 Physics Bldg, Durham, NC 27708

Selected Publications


Coulomb blockade correlations in a coupled single-electron device system

Journal Article Solid State Communications · July 1, 2019 Single-electron devices, such as metal single-electron transistor (SET) and semiconductor quantum dot (QD), are Coulomb blockade (CB) devices with promising applications in both quantum and classical beyond-Si information technologies. As an example, a cou ... Full text Cite

Observation of the Kondo effect in a quadruple quantum dot

Journal Article Physical Review B - Condensed Matter and Materials Physics · June 2, 2015 We investigate the Kondo effect in a quadruple-quantum-dot device of coupled double quantum dots (DQDs), which simultaneously contain intra-DQD and inter-DQD coupling. A variety of novel behaviors are observed. The differential conductance dI/dV is measure ... Full text Open Access Cite

Differential conductance oscillations in asymmetric quantum point contacts

Journal Article Physical Review B - Condensed Matter and Materials Physics · May 29, 2015 Small differential conductance oscillations as a function of source-drain bias are observed and systematically studied in an asymmetric quantum point contact. These oscillations become significantly suppressed in a small in-plane magnetic field (∼0.7 T) or ... Full text Cite

One-Dimensional Superconductivity in Nanowires

Book · April 15, 2013 The book introduces scientists and graduate students to superconductivity, and highlights the differences arising from the different dimensionality of the sample under study. It focuses on transport in one-dimensional superconductors, describing relevant t ... Full text Cite

Quasibound States and Evidence for a Spin 1 Kondo Effect in Asymmetric Quantum Point Contacts

Journal Article Physical Review B · 2013 Linear conductance below 2e2/h shows resonance peaks in highly asymmetric quantum point contacts (QPCs). As the channel length increases, the number of peaks also increases. At the same time, differential conductance exhibits zero bias anomalies (ZBAs) in ... Cite

Fabrication of submicron devices on the (011) cleave surface of a cleaved-edge-overgrowth GaAs/AlGaAs crystal

Journal Article Applied Physics Letters · March 19, 2012 We describe the fabrication of submicron devices on the (011) cleave surface of a GaAs heterostructure crystal, in which this surface is extremely narrow. Special purpose devices are produced, which take advantage of the unique characteristics of cleaved-e ... Full text Cite

Evidence for the formation of quasibound states in an asymmetrical quantum point contact

Journal Article Physical Review B - Condensed Matter and Materials Physics · February 10, 2012 Features below the first conductance plateau in ballistic quantum point contacts (QPCs) are often ascribed to electron interaction and spin effects within the single mode limit. In QPCs with a highly asymmetric geometry, we observe sharp resonance peaks wh ... Full text Cite

Controllable tunnel coupling and molecular states in a graphene double quantum dot

Journal Article Applied Physics Letters · January 9, 2012 We have measured a graphene double quantum dot device with multiple electrostatic gates that are used to enhance control to investigate it. At low temperatures, the transport measurements reveal honeycomb charge stability diagrams which can be tuned from w ... Full text Cite

Retrapping current, self-heating, and hysteretic current-voltage characteristics in ultranarrow superconducting aluminum nanowires

Journal Article Physical Review B - Condensed Matter and Materials Physics · November 8, 2011 Hysteretic I-V (current-voltage) curves are studied in narrow Al nanowires. The nanowires have a cross section as small as 50 nm2. We focus on the retrapping current in a down-sweep of the current, at which a nanowire re-enters the superconducting state fr ... Full text Open Access Cite

Switching currents limited by single phase slips in one-dimensional superconducting Al nanowires.

Journal Article Physical review letters · September 2011 An aluminum nanowire switches from superconducting to normal as the current is increased in an upsweep. The switching current (I(s)) averaged over upsweeps approximately follows the depairing critical current (I(c)) but falls below it. Fluctuations in I(s) ... Full text Open Access Cite

Gates controlled parallel-coupled double quantum dot on both single layer and bilayer graphene

Journal Article Applied Physics Letters · 2011 Here we report the fabrication and quantum transport measurements of gates controlled parallel-coupled double quantum dot on both bilayer and single layer graphene. It is shown that the interdot coupling strength of the parallel double dots can be effectiv ... Link to item Cite

The Kondo effect in coupled-quantum dots

Journal Article Reports on Progress in Physics · November 6, 2009 We discuss Kondo systems in coupled-quantum dots, with emphasis on the semiconductor quantum dot system. The rich variety of behaviors, such as distinct quantum phases, non-Fermi-liquid behavior and associated quantum phase transitions and cross-over behav ... Full text Cite

Crystal orientation and thickness dependence of the superconducting transition temperature of tetragonal FeSe1-x thin films.

Journal Article Physical review letters · September 2009 Superconductivity was recently found in the tetragonal phase FeSe. A structural transformation from tetragonal to orthorhombic (or monoclinic, depending on point of view) was observed at low temperature, but was not accompanied by a magnetic ordering as co ... Full text Cite

Growth and Investigation of Crystals of the New Superconductor alpha-FeSe from KC1 Solutions

Journal Article CRYSTAL GROWTH & DESIGN · July 2009 Crystals of FeSe0.88 and FeSeMn0.1 have been grown from KCl solutions. Crystals measuring 2-3 mm across and 0.1-0.3 mm thick grow with a hexagonal plate like habit. Powder X-ray diffraction (XRD) measurements show strong peaks corresponding to the tetragon ... Cite

The development of the superconducting PbO-type β-FeSe and related compounds

Journal Article Physica C: Superconductivity and its Applications · May 20, 2009 An overview of the recent development of the superconducting FeSe1-x and related compounds is presented. Methods to synthesize high purity polycrystalline samples, single crystals and thin films with preferred orientation are described. In addition to the ... Full text Cite

Spin-dependent resonant tunneling through 6 μm diameter double barrier resonant tunneling diode

Journal Article Applied Physics Letters · August 1, 2007 A vertical resonant tunneling diode based on the paramagnetic Zn1-x-y Mny Cdx Se system has been fabricated with a pillar diameter down to ∼6 μm. The diode exhibits high quality resonant tunneling characteristics through the electron subband of the quantum ... Full text Cite

Evidence for macroscopic quantum tunneling of phase slips in long one-dimensional superconducting Al wires.

Journal Article Physical review letters · July 2006 Quantum phase slips have received much attention due to their relevance to superfluids in reduced dimensions and to models of cosmic string production in the early universe. Their establishment in one-dimensional superconductors has remained controversial. ... Full text Cite

Coulomb blockade correlations in a coupled single-electron device system

Journal Article Solid State Communications · July 1, 2019 Single-electron devices, such as metal single-electron transistor (SET) and semiconductor quantum dot (QD), are Coulomb blockade (CB) devices with promising applications in both quantum and classical beyond-Si information technologies. As an example, a cou ... Full text Cite

Observation of the Kondo effect in a quadruple quantum dot

Journal Article Physical Review B - Condensed Matter and Materials Physics · June 2, 2015 We investigate the Kondo effect in a quadruple-quantum-dot device of coupled double quantum dots (DQDs), which simultaneously contain intra-DQD and inter-DQD coupling. A variety of novel behaviors are observed. The differential conductance dI/dV is measure ... Full text Open Access Cite

Differential conductance oscillations in asymmetric quantum point contacts

Journal Article Physical Review B - Condensed Matter and Materials Physics · May 29, 2015 Small differential conductance oscillations as a function of source-drain bias are observed and systematically studied in an asymmetric quantum point contact. These oscillations become significantly suppressed in a small in-plane magnetic field (∼0.7 T) or ... Full text Cite

One-Dimensional Superconductivity in Nanowires

Book · April 15, 2013 The book introduces scientists and graduate students to superconductivity, and highlights the differences arising from the different dimensionality of the sample under study. It focuses on transport in one-dimensional superconductors, describing relevant t ... Full text Cite

Quasibound States and Evidence for a Spin 1 Kondo Effect in Asymmetric Quantum Point Contacts

Journal Article Physical Review B · 2013 Linear conductance below 2e2/h shows resonance peaks in highly asymmetric quantum point contacts (QPCs). As the channel length increases, the number of peaks also increases. At the same time, differential conductance exhibits zero bias anomalies (ZBAs) in ... Cite

Fabrication of submicron devices on the (011) cleave surface of a cleaved-edge-overgrowth GaAs/AlGaAs crystal

Journal Article Applied Physics Letters · March 19, 2012 We describe the fabrication of submicron devices on the (011) cleave surface of a GaAs heterostructure crystal, in which this surface is extremely narrow. Special purpose devices are produced, which take advantage of the unique characteristics of cleaved-e ... Full text Cite

Evidence for the formation of quasibound states in an asymmetrical quantum point contact

Journal Article Physical Review B - Condensed Matter and Materials Physics · February 10, 2012 Features below the first conductance plateau in ballistic quantum point contacts (QPCs) are often ascribed to electron interaction and spin effects within the single mode limit. In QPCs with a highly asymmetric geometry, we observe sharp resonance peaks wh ... Full text Cite

Controllable tunnel coupling and molecular states in a graphene double quantum dot

Journal Article Applied Physics Letters · January 9, 2012 We have measured a graphene double quantum dot device with multiple electrostatic gates that are used to enhance control to investigate it. At low temperatures, the transport measurements reveal honeycomb charge stability diagrams which can be tuned from w ... Full text Cite

Retrapping current, self-heating, and hysteretic current-voltage characteristics in ultranarrow superconducting aluminum nanowires

Journal Article Physical Review B - Condensed Matter and Materials Physics · November 8, 2011 Hysteretic I-V (current-voltage) curves are studied in narrow Al nanowires. The nanowires have a cross section as small as 50 nm2. We focus on the retrapping current in a down-sweep of the current, at which a nanowire re-enters the superconducting state fr ... Full text Open Access Cite

Switching currents limited by single phase slips in one-dimensional superconducting Al nanowires.

Journal Article Physical review letters · September 2011 An aluminum nanowire switches from superconducting to normal as the current is increased in an upsweep. The switching current (I(s)) averaged over upsweeps approximately follows the depairing critical current (I(c)) but falls below it. Fluctuations in I(s) ... Full text Open Access Cite

Gates controlled parallel-coupled double quantum dot on both single layer and bilayer graphene

Journal Article Applied Physics Letters · 2011 Here we report the fabrication and quantum transport measurements of gates controlled parallel-coupled double quantum dot on both bilayer and single layer graphene. It is shown that the interdot coupling strength of the parallel double dots can be effectiv ... Link to item Cite

The Kondo effect in coupled-quantum dots

Journal Article Reports on Progress in Physics · November 6, 2009 We discuss Kondo systems in coupled-quantum dots, with emphasis on the semiconductor quantum dot system. The rich variety of behaviors, such as distinct quantum phases, non-Fermi-liquid behavior and associated quantum phase transitions and cross-over behav ... Full text Cite

Crystal orientation and thickness dependence of the superconducting transition temperature of tetragonal FeSe1-x thin films.

Journal Article Physical review letters · September 2009 Superconductivity was recently found in the tetragonal phase FeSe. A structural transformation from tetragonal to orthorhombic (or monoclinic, depending on point of view) was observed at low temperature, but was not accompanied by a magnetic ordering as co ... Full text Cite

Growth and Investigation of Crystals of the New Superconductor alpha-FeSe from KC1 Solutions

Journal Article CRYSTAL GROWTH & DESIGN · July 2009 Crystals of FeSe0.88 and FeSeMn0.1 have been grown from KCl solutions. Crystals measuring 2-3 mm across and 0.1-0.3 mm thick grow with a hexagonal plate like habit. Powder X-ray diffraction (XRD) measurements show strong peaks corresponding to the tetragon ... Cite

The development of the superconducting PbO-type β-FeSe and related compounds

Journal Article Physica C: Superconductivity and its Applications · May 20, 2009 An overview of the recent development of the superconducting FeSe1-x and related compounds is presented. Methods to synthesize high purity polycrystalline samples, single crystals and thin films with preferred orientation are described. In addition to the ... Full text Cite

Spin-dependent resonant tunneling through 6 μm diameter double barrier resonant tunneling diode

Journal Article Applied Physics Letters · August 1, 2007 A vertical resonant tunneling diode based on the paramagnetic Zn1-x-y Mny Cdx Se system has been fabricated with a pillar diameter down to ∼6 μm. The diode exhibits high quality resonant tunneling characteristics through the electron subband of the quantum ... Full text Cite

Evidence for macroscopic quantum tunneling of phase slips in long one-dimensional superconducting Al wires.

Journal Article Physical review letters · July 2006 Quantum phase slips have received much attention due to their relevance to superfluids in reduced dimensions and to models of cosmic string production in the early universe. Their establishment in one-dimensional superconductors has remained controversial. ... Full text Cite

The Kondo effect and controlled spin entanglement in coupled double-quantum-dots

Conference AIP Conference Proceedings · July 8, 2005 Semiconductor double-quantum dots represent an ideal system for studying the novel spin physics of localized spins. On each quantum dot when the number of electrons is odd and the net spin is 1/2, a strong coupling of this localized spin to conducting elec ... Full text Cite

Ultranarrow AuPd and Al Wires

Journal Article Applied Physics Letters · 2005 In this letter, we discuss a versatile template technique aimed to the fabrication of sub-10 nm wide wires. Using this technique, we have measured AuPd wires, 12 nm wide and as long as 20 µm. Even materials that form a strong superficial oxide, an ... Link to item Cite

Transition between Quantum States in a Parallel-Coupled Double Quantum Dot

Journal Article Physical Review Letters · April 2004 Strong electron and spin correlations in a double quantum dot (DQD) can give rise to different quantum states.We observe a continuous transition from a Kondo state exhibiting a single-peak Kondo resonance to another exhibiting a double peak by increas ... Cite

Chiral Luttinger Liquids at the Fractional Quantum Hall Edge

Journal Article Review of Modern Physics · October 2003 http://ojps.aip.org/dbt/dbt.jsp?KEY=RMPHAT&Volume=75&Issue=4 ... Cite

Is the chiral Luttinger liquid exponent universal?

Journal Article Comptes Rendus Physique · July 1, 2002 We present experimental evidence from electron tunneling measurements that the chiral Luttinger liquid power-law exponent, α, for tunneling into the fractional quantum Hall edge deviates substantially from the universal behavior predicted by theory. Our re ... Full text Cite

The lever-arm model: Describing resonant tunneling under bias at a fractional quantum Hall edge

Journal Article Physica E: Low-Dimensional Systems and Nanostructures · January 1, 2002 New tunnel current measurements of resonant tunneling at voltage-biased quantum Hall effect edge were reported. Results showed that the tunneling density of states at a sharp quantum Hall edge obeyed a power-law form. The fits to this data demonstrated the ... Full text Cite

The Kondo effect in an artificial quantum dot molecule.

Journal Article Science (New York, N.Y.) · September 2001 Double quantum dots provide an ideal model system for studying interactions between localized impurity spins. We report on the transport properties of a series-coupled double quantum dot as electrons are added one by one onto the dots. When the many-body m ... Full text Cite

Resistance of a perfect wire

Journal Article Nature · May 3, 2001 Intuition tells us that a wire without defects should have zero resistance. But in the real world all conductors, however perfect, have some resistance. A new study confirms that electrical contacts are the problem. ... Full text Cite

Resonant tunneling into a biased fractional quantum Hall edge

Journal Article Physical Review Letters · March 19, 2001 The voltage dependence of a new type of resonance at a sharp fractional quantum Hall effect (FQHE) edge was characterized. Clear non-Fermi liquid (non-FL) behavior through line shape analysis and nonconservation of resonance area was demonstrated. ... Full text Cite

Quantum chaos in GaAs/AlxGa1-xAs microstructures

Conference Physica Scripta T · January 1, 2001 We review clear signatures of "quantum chaos" observable in both open and closed systems realized in GaAs/AlxGa1-xAs microstructures. In open ballistic billiards where scattering dynamics determine the characteristics of quantum transport, we find a striki ... Cite

Plateau behavior in the chiral Luttinger liquid exponent

Journal Article Physical Review Letters · January 1, 2001 Results indicating the presence of a plateau feature for the α versus 1/v dependence with an α value close to 3 are discussed. These results have been obtained in two sets of samples studied via analysis of I-V tunneling data and statistical F-test. ... Full text Cite

Quantum chaos in GaAs/AlxGa1-xAs microstructures

Conference Physica Scripta T · 2001 We review clear signatures of "quantum chaos" observable in both open and closed systems realized in GaAs/AlxGa1-xAs microstructures. In open ballistic billiards where scattering dynamics determine the characteristics of quantum transport, we find a striki ... Cite

Chiral Luttinger Liquids at the Fractional Quantum Hall Edge

Conference Proceedings of the Centennial OCPA conference · 1999 Cite

Hebbian learning in the agglomeration of conducting particles

Journal Article Phys. Rev. E (Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics) · 1999 Link to item Cite

An apparent g = 1/2 chiral Luttinger liquid at the edge of the v = 1/2 compressible composite Fermion liquid

Conference Physica B: Condensed Matter · June 17, 1998 The conductance (G) and current-voltage (I - V) characteristics are investigated for electron tunneling into the edge of the v = 1/2 gapless quantum Hall composite Fermion liquid. A non-linear, power law I-V and a power-law temperature dependence in G are ... Full text Cite

Structure and correlations of the flux line lattice in crystalline nb through the peak effect

Journal Article Physical Review Letters · January 1, 1998 We have measured the structure of the field cooled flux line lattice (FLL) in single crystal Nb using small angle neutron scattering. Augmented by transport and thermodynamic data, a scenario for the dramatic disordering of the FLL near the peak effect eme ... Full text Cite

Continuum of chiral luttinger liquids at the fractional quantum hall edge

Journal Article Physical Review Letters · January 1, 1998 We study current versus voltage (I-V) when tunneling into the edge of the fractional quantum Hall effect over a continuum of filling factors (ν) from 1/4 to 1. Our devices manifest the power law I-V behavior previously observed by Chang et al. at discrete ... Full text Cite

Quantum chaos in Ga/AlxGa1-xAs microstructures

Journal Article Chaos, Solitons and Fractals · January 1, 1997 We report distinct signatures of 'quantum chaos' in both open and closed systems. Quantum chaos refers to the quantum signature of systems which classically exhibit chaotic dynamics. In the open case, we measure the line shape of the negative magneto-resis ... Full text Cite

Quantum chaos in Ga/AlxGa1-xAs microstructures

Journal Article Chaos, Solitons and Fractals · 1997 We report distinct signatures of 'quantum chaos' in both open and closed systems. Quantum chaos refers to the quantum signature of systems which classically exhibit chaotic dynamics. In the open case, we measure the line shape of the negative magneto-resis ... Cite

Tunneling current noise in thin gate oxides

Journal Article Applied Physics Letters · November 4, 1996 We have examined fluctuations in the tunneling current of 3.5 nm SiO2 barriers for voltages in the direct tunneling regime. We find a 1/f power law for the spectral density of the fluctuations where f is the frequency. This 1/f noise can be attributed to f ... Full text Cite

Observation of Chiral Luttinger Behavior in Electron Tunneling into Fractional Quantum Hall Edges

Journal Article Physical Review Letters · January 1, 1996 We measure the tunneling conductance (G) and current-voltage (I–V) characteristics for electron tunneling from a bulk doped-GaAs normal metal into the abrupt edge of a fractional quantum Hall effect. We observe clear power law behavior for both the I–V rel ... Full text Cite

Penetration of laterally quantized flux lamina into a superconducting wire network

Journal Article Solid State Communications · January 1, 1996 We report direct, high resolution images of the magnetic field above a superconducting wire grid as applied flux penetrates into an initially empty state or into a state with half the plaquettes containing a magnetic quantum. We find two qualitatively diff ... Full text Cite

1/f noise in the tunneling current of thin gate oxides

Journal Article Materials Research Society Symposium - Proceedings · January 1, 1996 We have observed fluctuations in the tunneling current through 3.5 nm gate oxides with a 1/f power spectrum where f is the frequency. For voltages in the direct tunneling regime we find an anomalous current dependence of the noise relative to previous obse ... Full text Cite

High-resolution scanning hall probe microscopy

Conference Proceedings of SPIE - The International Society for Optical Engineering · June 4, 1993 A high resolution scanning Hall probe microscope is used to spatially resolve vortices in high temperature superconducting Bi2Sr2CaCu2O8+δ crystals. We observe a partially ordered vortex lattice at several different applied magnetic fields and temperatures ... Full text Cite

Direct spatial imaging of vortices in a superconducting wire network

Journal Article Physical Review Letters · January 1, 1993 We report direct observations of vortices in a square superconducting wire grid imaged using scanning Hall probe microscopy. Real space images of vortex configurations are obtained as a function of the flux per unit cell f by measuring the local magnetic f ... Full text Cite

Scanning hall-probe microscopy of a vortex and field fluctuations in La1.85Sr0.15CuO4 films

Journal Article EPL · December 1, 1992 A high-resolution scanning Hall-probe microscope is used to spatially resolve vortices in high-temperature superconducting La1.85Sr0.15CuO4 films. At low magnetic fields, a disordered vortex arrangement is observed. A fit to the surface field of an individ ... Full text Cite

Transport evidence for phase separation into spatial regions of different fractional quantum Hall fluids near the boundary of a two-dimensional electron gas

Journal Article Physical Review Letters · January 1, 1992 Near the boundary, a 2D electron gas can phase separate into fractional quantum Hall fluid regions of successively lower filling factors (ν), in the case of a slowly increasing boundary potential. We present experimental evidence in the ν=1/3, 2/3, and 1 q ... Full text Cite

Quantum interference effects and spin-orbit interaction in quasi-one-dimensional wires and rings

Journal Article Physical Review B · January 1, 1992 We study two kinds of quantum interference effects in transportthe Aharonov-Bohm effect and the weak-localization effectin quasi-one-dimensional wires and rings to address issues concerning the phase-coherence length, spin-orbit scattering, and the flux ca ... Full text Cite

Scanning Hall probe microscopy

Journal Article Applied Physics Letters · January 1, 1992 We describe the implementation of a scanning Hall probe microscope of outstanding magnetic field sensitivity (∼0.1 G) and unprecedented spatial resolution (∼0.35 μm) to detect surface magnetic fields at close proximity to a sample. Our microscope combines ... Full text Cite

Effects of substrate orientation, pseudomorphic growth and superlattice on alloy scattering in modulation doped GaInAs

Journal Article Journal of Crystal Growth · May 2, 1991 The possibility of reducing alloy scattering in MBE Ga1-xInxAs has been studied experimentally by growing modulation doped heterostructures (A) with an InAs/GaInAs superlattice 2DEG channel, (B) on a vicinal (110) InP substrate, and (C) with a strain compe ... Full text Cite

QUENCHING OF THE HALL RESISTANCE IN A NOVEL GEOMETRY

Journal Article Modern Physics Letters B · January 10, 1991 We review experiments on the observation of Hall resistance anomalies in ballistic Hall junctions of novel geometries, in submicron GaAs-Al x Ga 1−x As heterostructure devices. We demo ... Full text Cite

Quenching of the Hall effect in a novel geometry

Journal Article Surface Science · April 2, 1990 We study the Hall effect at low magnetic fields in ballistic GaAs-AlxGa1 - xAs heterostructure Hall junctions that contain four, three, two, or one narrow constrictions in the junction region. These geometries are investigated to determine the necessary co ... Full text Cite

Transmission and reflection probabilities between the ν=1 and the ν= 2 3 quantum hall effects

Journal Article Surface Science · April 2, 1990 We report a transport experiment in the quantum Hall regime on the transmission of electron waves from a region exhibiting the ν=1 integral quantum Hall effect, through a barrier region exhibiting the ν= 2 3 fractional quantum Hall effect. Our work represe ... Full text Cite

A unified transport theory for the integral and fractional quantum hall effects: Phase boundaries, edge currents, and transmission/reflection probabilities

Journal Article Solid State Communications · January 1, 1990 We propose a unified transport theory for the fractional (FQHE) and integral quantum Hall effect (IQHE) of the Buttiker-Landauer type in the presence of smooth confinement and impurity potentials, where resistances are expressed in terms of transmission an ... Full text Cite

Quenching of the Hall resistance in a novel geometry.

Journal Article Physical review letters · August 1989 Full text Cite

Spatial localization of Si in selectively δ-doped AlxGa1-xAs/GaAs heterostructures for high mobility and density realization

Journal Article Journal of Crystal Growth · February 2, 1989 We report on a new type of structure formed by δ-doping the barrier of an AlxGa1-xAs/GaAs heterostructure. We investigate transport in these structures which reveal that very high quality fractional quantum hall structure occurs as well as systematically h ... Full text Cite

Transmission and reflection probabilities between ν=1 and ν= 2 3 quantum Hall effects and between ν= 2 3 and ν= 1 3 effects

Journal Article Solid State Communications · January 1, 1989 We perform transport experiments in the quantum Hall regime on transmission through a barrier region exhibiting a fractional quantum Hall effect. For transmission from the ν=1 effect through a barrier at the 2 3 effect, the transmission probability is 2 3( ... Full text Cite

Fabrication of gatable submicron channels in AlxGa 1-xAs-GaAs heterostructures

Journal Article Applied Physics Letters · December 1, 1988 A new, simplified process has been developed for fabricating submicron AlxGa1-xAs-GaAs heterostructure devices for low-temperature transport studies, with the advantage of gatability. This process utilizes electron beam lithography, photolithography, and w ... Full text Cite

Observation of phase-shift locking of the Aharonov-Bohm effect in doubly connected GaAsAlxGa1-xAs heterostructure devices

Journal Article Solid State Communications · January 1, 1988 We have observed a tendency toward locking of the Aharonov-Bohm effect phase shift, in doubly connected, quasi-one-dimensional GaAsAlxGa1-xAs devices. The resistances of adjacent segments within a device exhibit periodic modulations, due to magnetic flux p ... Full text Cite

Magneto-quantum transport in a quasi-one-dimensional GaAs/AlxGa1-xAs ring

Journal Article Surface Science · January 1, 1988 We study the magneto-transport properties of a quasi-ID GaAs/AlxGa1-xAs ring of mobility 40 000 cm2/V·a at 4 K. The inelastic scattering length is about 4000 Å while the sample length is of the order of 3 μm, so that we are in the diffusive regime. A varie ... Full text Cite

Quantum size effect in monolayer-doped heterostructures

Journal Article Physical Review B · January 1, 1988 We report molecular-beam-epitaxial growth of a new structure formed by monolayer doping the barrier of an AlxGa1-xAs-GaAs heterojunction. Our investigations of these structures include the quantum Hall effect and variable temperature mobility measurements, ... Full text Cite

Deviation of the quantum hall effect from exact quantization in narrow GaAs-AlxGa1-xAs heterostructure devices

Journal Article Solid State Communications · January 1, 1988 We report the first observation of deviaton of the i=4 quantum Hall plateau from its quantized value, in narrow GaAs-AlxGa1-xAs quasi-1-d wires of width 2000A. The deviation arises in the form of aperiodic fluctuations as the magnetic field is varied, even ... Full text Cite

Quantum transport in one-dimensional GaAs/AlGaAs microstructures

Journal Article Surface Science · January 1, 1988 We have observed the Aharonov-Bohm effect in the magnetoresistance of doubly connected geometries fabricated in high mobility GaAs/AlGaAs heterostructures. Periodic oscillations in the resistance associated with the magnetic fluxes θ0 = hc/e, θ0/2, and θ0/ ... Full text Cite

Quantum transport in quasi-one-dimensional GaAsAlxGa1-xAs heterostructure devices

Journal Article Superlattices and Microstructures · January 1, 1988 We study quantum transport properties of narrow GaAsAlxGa1-xAs wires and rings made by electron beam lithography. At low temperatures, clear signatures of Ah́aronov-Bohm quantum interference effects are observed due to the application of a perpendicular mag ... Full text Cite

Activation energies and localization in the fractional quantum Hall effect

Journal Article Physical Review B · January 1, 1987 This paper summarizes an extensive study of the temperature dependence of magnetotransport in the fractional quantum Hall effect in GaAs-AlxGa1-xAs heterostructure devices of varying mobility and density. For devices with electron mobility 400 000 1 000 00 ... Full text Cite

Quantum transport in an electron-wave guide

Journal Article Physical Review Letters · January 1, 1987 We have fabricated high-mobility, one dimensional wires in GaAs-AlGaAs heterostructures and measured the resistance as a function of magnetic field and temperature. Because of the size of the devices and the high mobility, only a few channels carry the cur ... Full text Cite

Critical currents of the quantum Hall effect in the mesoscopic regime

Journal Article Physical Review B · January 1, 1987 The critical currents associated with the breakdown of the quantum Hall effect have been measured in high-mobility, one-dimensional channels fabricated in GaAs-AlxGa1-xAs heterostructures. The results differ in several respects from the breakdown in macros ... Full text Cite

Observation of the Aharonov-Bohm effect for c>1

Journal Article Physical Review Letters · January 1, 1987 We have observed the Aharonov-Bohm effect in the magnetoresistance of doubly connected geometries fabricated in high-mobility GaAs/AlGaAs heterostructures. Periodic oscillations in the resistance associated with the fluxs penetrating the annulus are suppre ... Full text Cite

Two-dimensional electron gas in a Ga0.47In0.53As/InP heterojunction grown by chemical beam epitaxy

Journal Article Applied Physics Letters · December 1, 1986 Shubnikov-de Haas, quantum Hall effect, and cyclotron resonance measurements revealed the existence of a high mobility, two-dimensional electron gas at the Ga0.47In0.53As/InP heterointerface grown by chemical beam epitaxy. Enhanced electron mobilities were ... Full text Cite

Activation energies of fundamental and higher order states in the fractional quantum Hall effect

Journal Article Surface Science · April 3, 1986 We report a systematic study of activation energies for the fundamental states in the fractional quantum Hall effect at Landau level filling factors v = 1 3, 2 3, and 5 3 in magnetic fields to 28 T. We also present activation energies for the higher order ... Full text Cite

An experimental test of two-parameter scaling of integral quantum Hall effect

Journal Article Surface Science · April 3, 1986 Detailed measurements are made of the temperature and magnetic field dependences of the magneto-transport coefficients, σxx and σxy, in an In0.53Ga0.47AsInP heterostructure to test the (two-parameter) renormalization group theory of the integral quantum Ha ... Full text Cite

BREAKDOWN OF THE INTEGRAL QUANTUM HALL EFFECT.

Conference · December 1, 1985 We report experimental results on the breakdown of the low-dissipation currents in the integral quantum Hall effect at temperatures from 6 to 0. 5K, and in magnetic fields up to 28T using Corbino-ring geometry. The Hall current at which the abrupt breakdow ... Cite

Introduction to Tunneling in Biology

Journal Article Comments on Molecular and Cellular Biology · 1985 Cite

Competition between neighboring minima in the fractional quantum Hall effect

Journal Article Physical Review B · January 1, 1985 We report observations of a temperature-dependent competition in the fractional quantum Hall effect in GaAs/AlGaAs heterostructures. Two pairs of neighboring minima in the diagonal resistance xx versus magnetic field exhibit a competition by which the stro ... Full text Cite

Magnetic field dependence of activation energies in the fractional quantum hall effect

Journal Article Physical Review Letters · January 1, 1985 We have studied the temperature dependence of the fractional quantum Hall effect at Landaulevel filling factors =13, 23, 43, 53, 25, and 35 in magnetic fields up to 28 T to determine the magnitude of the associated energy gaps. The data suggest a single ac ... Full text Cite

Temperature dependence of the quantized Hall effect

Journal Article Physical Review B · January 1, 1985 We reported detailed measurements of the temperature dependence of the quantized Hall effect from 4.2 to 50 K in the i=2 plateau region in InGaAs-InP. We deduce from the data that there is a significant density of localized states between the two Landau le ... Full text Cite

Distribution of the quantized Hall potential in GaAs-AlxGa1-xAs heterostructures

Journal Article Physical Review B · January 1, 1985 We report measurements of the Hall potential distribution in the interior of the two-dimensional electron gas in GaAs-AlxGa1-xAs heterostructures. In the quantized Hall regime, our data provide direct evidence for the existence of extended states in the bu ... Full text Cite

Experimental observation of a striking similarity between quantum hall transport coefficients

Journal Article Solid State Communications · January 1, 1985 The derivative of the Quantum Hall resistance, ρxy, with respect to the carrier density, n, has been measured for a two-dimensional electron gas in a GaAs-AlxGa1-xAs heterostructure, as a function of magnetic field. dρxy/dn exhibits a remarkable similarity ... Full text Cite

Fractional quantum hall effect at low temperatures

Journal Article Surface Science · July 1, 1984 We report results of low temperature (65 mK to 770 mK) magneto-transport measurements of the 2 3 quantum Hall plateau in an n-type GaAsAlxGa1-x As heterostructure. Both the diagonal resistivity ρ{variant}xx and the deviation of the Hall resistivity ρ{varia ... Full text Cite

Higher-order states in the multiple-series, fractional, quantum hall effect

Journal Article Physical Review Letters · January 1, 1984 We report results on the fractional quantum Hall effect in GaAs-AlxGa1-xAs heterostructures at fractional Landau-level filling factor 1/2=pq obtained with the combination of a dilution refrigerator and the National Magnet Laboratory hybrid magnet. We estab ... Full text Cite

Fractional quantization of the hall effect

Journal Article Physical Review Letters · January 1, 1983 Magnetotransport of two-dimensional electrons and holes was studied in magnetic fields up to 300 kG and temperatures down to 0.5 K. In addition to previously reported structures at Landau-level filling factors =13 and 23, new structures were resolved at =4 ... Full text Cite

Fractional quantum Hall effect at low temperatures

Journal Article Physical Review B · January 1, 1983 We report a systematic study of the 23 fractional quantum Hall effect at low temperatures (65-770 mK) for a GaAs-AlxGa1-xAs sample of very high mobility (106 cm2/V sec). We find the 23 Hall plateau to be accurately quantized. The diagonal and Hall resistiv ... Full text Cite

Energy structure and quantized hall effect of two-dimensional holes

Journal Article Physical Review Letters · January 1, 1983 Combined magnetotransport and cyclotron-resonance experiments in a two-dimensional hole system at a modulation-doped GaAs-(AlGa)As heterojunction show that the Kramers degeneracy of the lowest subband is lifted for finite k giving rise to two cyclotron mas ... Full text Cite

Electron tunneling in cytochrome c

Journal Article The Journal of Chemical Physics · January 1, 1982 An upper limit for the extinction coefficient of the charge transfer band in the ferrohexacyanide-ferricytochrome c redox couple has been determined from 800 to 1800 nm. We obtain ε≤0.003 M-1 cm-1 between 800-1400 nm, ε≤0.02 M-1 cm-1 between 1400-1800 nm. ... Full text Cite

Effects of interatomic attraction on total cross sections in curve crossing collisions

Journal Article The Journal of Chemical Physics · January 1, 1978 We consider the influence of long range forces on the total cross section for a two-state curve crossing process. If the upper potential curve V 22(R) is attractive and behaves as R -n for R beyond the crossing point, a centrifugal barrier will arise which ... Full text Cite