Scholars@Duke
Alexander Y. Kozhanov

Alexander Y. Kozhanov

Associate Research Professor in the Department of Electrical and Computer Engineering
Electrical and Computer Engineering

Selected Publications

Next-generation trapped-ion quantum computing system

Conference Quantum 2.0: Proceedings Optica Quantum 2.0 Conference and Exhibition · January 1, 2023 In this work we discuss the progress of commissioning the next-generation trapped-ion quantum computing system. Heating rates, coherence times, background gas collision rates, individual-addressing cross-talk and other factors contributing to the gate fide ... Full text Cite

Exchange bias without directional anisotropy in permalloy/CoO bilayers

Journal Article Physical Review B · October 1, 2021 We utilize transverse ac susceptibility measurements to characterize magnetic anisotropy in archetypal exchange-bias bilayers of ferromagnet permalloy (Py) and antiferromagnet CoO. Unidirectional anisotropy is observed for thin Py but becomes negligible at ... Full text Open Access Cite

Analysis of useful ion yield for Si in GaN by secondary ion mass spectrometry

Journal Article Journal of Vacuum Science and Technology B · July 1, 2020 The optimum detection levels that can be achieved by a secondary ion mass spectrometer are dependent on how efficiently a particular species of interest can be ionized and detected. One can determine in advance whether the analysis of a particular ion in t ... Full text Cite

Analysis of useful ion yield for the Mg dopant in GaN by quadrupole—SIMS

Journal Article Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena · May 1, 2020 The authors present a quantitative secondary ion mass spectrometry (SIMS) analysis of the useful ion yield of magnesium dopant in a gallium nitride matrix. A quadrupole SIMS instrument was used to analyze an Mg-doped GaN sample grown by metal organ ... Full text Cite

Kinetically stabilized high-temperature InN growth

Journal Article Journal of Crystal Growth · April 15, 2020 We report on indium nitride growth on sapphire substrates by migration-enhanced plasma-assisted metal organic chemical vapor deposition (MEPA-MOCVD). The growth is studied in the temperature range from 700 °C to 957 °C, well above the decomposition tempera ... Full text Cite

Influence of plasma-activated nitrogen species on PA-MOCVD of InN

Journal Article Applied Physics Letters · November 25, 2019 We report on the influence of various plasma species on the growth and structural properties of indium nitride in plasma-assisted metalorganic chemical vapor deposition. Atomic emission spectroscopy was used to quantify the molecular, neutral, and ionized ... Full text Cite

High-Frequency/High-Field Electron Paramagnetic Resonance and Theoretical Studies of Tryptophan-Based Radicals.

Journal Article The journal of physical chemistry. A · March 2018 Tryptophan-based free radicals have been implicated in a myriad of catalytic and electron transfer reactions in biology. However, very few of them have been trapped so that biophysical characterizations can be performed in a high-precision context. In this ... Full text Cite

Magnetic droplet solitons generated by pure spin currents

Journal Article Physical Review B · December 14, 2017 Magnetic droplets are dynamical solitons that can be generated by locally suppressing the dynamical damping in magnetic films with perpendicular anisotropy. To date, droplets have been observed only in nanocontact spin-torque oscillators operated by spin-p ... Full text Cite

Nanoconstriction spin-Hall oscillator with perpendicular magnetic anisotropy

Journal Article Applied Physics Letters · July 17, 2017 We experimentally study spin-Hall nano-oscillators based on [Co/Ni] multilayers with perpendicular magnetic anisotropy. We show that these devices exhibit single-frequency auto-oscillations at current densities comparable to those for in-plane magnetized o ... Full text Cite

Tunable configurational anisotropy of concave triangular nanomagnets

Journal Article Journal of Applied Physics · June 21, 2016 Shape and dimension variation effects on the configurational anisotropy and magnetization ground states of single domain triangular nano-magnets are investigated using micromagnetic simulations and magnetic force microscopy. We show that introducing concav ... Full text Cite

Magnonic Logic Devices

Chapter · February 19, 2016 Full text Cite

Spin wave scattering and interference in ferromagnetic cross

Journal Article Journal of Applied Physics · October 28, 2015 Magnetostatic spin wave scattering and interference across a CoTaZr ferromagnetic spin wave waveguide cross junction were investigated experimentally and by micromagnetic simulations. It is observed that the phase of the scattered waves is dependent on the ... Full text Cite

Gaps and pseudogaps in perovskite rare earth nickelates

Journal Article APL Materials · June 1, 2015 We report on tunneling measurements that reveal the evolution of the quasiparticle state density in two rare earth perovskite nickelates, NdNiO3 and LaNiO3, that are close to a bandwidth controlled metal to insulator transition. We me ... Full text Cite

Cross junction spin wave logic architecture

Journal Article IEEE Transactions on Magnetics · November 1, 2014 Backward volume magnetostatic spin wave interference in ferromagnetic cross is explored. Spin waves are excited at the two input arms of the cross, interference signal amplitude, and phase are detected in the other two, output arms of the cross. Spin wave ... Full text Cite

Structural and transport properties of epitaxial PrNiO3 thin films grown by molecular beam epitaxy

Journal Article Journal of Crystal Growth · January 1, 2013 Epitaxial single crystal films of praseodymium nickelate (PrNiO 3) have been grown by molecular beam epitaxy on LaAlO 3(001) substrates. In-situ electron diffraction and ex-situ X-ray diffraction techniques confirm an epitaxial relationship to the underlyi ... Full text Cite

Inelastic light scattering from terahertz standing waves in a slab waveguide

Journal Article Journal of the Optical Society of America B: Optical Physics · October 1, 2012 Second order, X(2) nonlinear mixing of optical and terahertz (THz) radiation is enhanced by phase matching by the spatial distribution of THz standing waves in a slab waveguide. The interference pattern due to selectively excited waveguide modes is thus de ... Full text Cite

Spin wave modes in ferromagnetic tubes

Journal Article Journal of Applied Physics · January 1, 2012 Resonances are observed in the transmission between two coplanar waveguides coupled by ferromagnetic Co 90Ta 5Zr 5 tubes that wrap around their shorted ends. The resonances are assigned to the magnetostatic surface waves that counter propagate along the tu ... Full text Cite

Martensite transformation of epitaxial Ni-Ti films

Journal Article Applied Physics Letters · May 9, 2011 The structure and phase transformations of thin Ni-Ti shape memory alloy films grown by molecular beam epitaxy are investigated for compositions from 43 to 56 at. % Ti. Despite the substrate constraint, temperature dependent x-ray diffraction and resistivi ... Full text Cite

Micro-structured ferromagnetic tubes for spin wave excitation

Journal Article Journal of Applied Physics · April 1, 2011 Micron scale ferromagnetic tubes placed on the ends of ferromagnetic CoTaZr spin waveguides are explored in order to enhance the excitation of backward volume magnetostatic spin waves. The tubes produce a closed magnetic circuit about the signal line of th ... Full text Cite

Transport in ferromagnetic GdTiO3 / SrTiO3 heterostructures

Journal Article Applied Physics Letters · March 14, 2011 Epitaxial GdTiO3 / SrTiO3 structures with different SrTiO3 layer thicknesses are grown on (001) (LaAlO3) 0.3 (Sr2 AlTaO6) 0.7 substrate surfaces by hybrid molecular beam epitaxy. It is shown that the formation of the pyrochlore (Gd2 Ti2 O7) phase can be av ... Full text Cite

Dispersion and spin wave "tunneling" in nanostructured magnetostatic spin waveguides

Journal Article Journal of Applied Physics · April 27, 2009 Magnetostatic spin wave dispersion and loss are measured in micron scale spin waveguides in ferromagnetic, metallic CoTaZr. Results are in good agreement with model calculations of spin wave dispersion. The measured attenuation lengths, of the order of 3 μ ... Full text Cite

Dispersion in magnetostatic CoTaZr spin waveguides

Journal Article Applied Physics Letters · January 19, 2009 Magnetostatic spin wave dispersion and loss are measured in micron scale spin waveguides in ferromagnetic metallic CoTaZr. Results are in good agreement with model calculations of spin wave dispersion and up to three different modes are identified. Attenua ... Full text Cite

Magnetostatic spin-wave modes in ferromagnetic tube

Journal Article IEEE Transactions on Magnetics · January 1, 2009 Magnetostatic spin-wave modes were excited and detected in micron size ferromagnetic Co Ta Zr rectangular tubes that wrapped around the shorted ends of coplanar waveguides. The observed modes can be assigned to surface spin waves of an infinite ferromagnet ... Full text Cite

Photoconductivity of the Pb0.75Sn0.25Te:In alloy in an alternating electric field

Journal Article Semiconductors · January 1, 2007 Kinetics of variations in the components of total impedance for single-crystal Pb0.75Sn0.25Te:In samples is investigated upon switching on and switching off of the illumination source at temperature 4.2 K and frequency 106 Hz. The calculation carried out i ... Full text Cite

Conductivity of Pb1-x SnxTe:In solid solutions in an ac electric field

Journal Article Semiconductors · September 1, 2006 The frequency and temperature dependences of components of the impedance of Pb0.75Sn0.25Te:In single crystals are studied within the frequency range from 20 to 106 Hz and at temperatures from 4.2 to 300 K. Impedance spectra are analyzed using the equivalen ... Full text Cite

New type of sensitive infrared and submillimeter radiation photodetectors

Conference Proceedings of SPIE - The International Society for Optical Engineering · October 24, 2005 Doping of the lead telluride and related alloys with the group III impurities results in appearance of the unique physical features of a material, such as persistent photoresponse, enhanced responsive quantum efficiency (up to 100 photoelectrons/incident p ... Full text Cite

Submillimeter radiation - Induced persistent photoconductivity in Pb 1-xTE(In)

Conference Proceedings of SPIE - The International Society for Optical Engineering · December 1, 2004 Persistent photoconductivity in a Pb0.75Sn0.25Te(In) alloy initiated by monochromatic submillimeter-range radiation at wavelengths of 176 and 241 μm was observed at helium temperatures. This photoconductivity is shown to be associated with optical excitati ... Full text Cite

Photoconductivity of Lead Telluride-Based Doped Alloys in the Submillimeter Wavelength Range

Journal Article Physics of the Solid State · January 1, 2004 Persistent photoconductivity in a Pb0.75Sn0.25Te(In) alloy initiated by monochromatic submillimeter-range radiation at wavelengths of 176 and 241 μm was observed at helium temperatures. This photoconductivity is shown to be associated with optical excitati ... Full text Cite

Fermi Level Pinning and Negative Magnetoresistance in PbTe:(Mn, Cr)

Journal Article Semiconductors · January 1, 2004 Fermi level pinning and persistent photoconductivity are observed in PbTe:(Mn, Cr) at T < 35 K. The impurity level that pins the chemical potential level shifts toward the bottom of the conduction band with increasing manganese content. Negative magnetores ... Full text Cite

Negative magnetoresistance in PbTe(Mn,Cr)

Journal Article International Journal of Modern Physics B · August 30, 2002 We have observed the negative magnetoresistance effect in the narrow-gap PbTe(Mn,Cr) semiconductor, in which the Fermi level is pinned within the gap nearby the conduction band edge. Previously the giant negative magentoresistance effect has been reported ... Full text Cite

NEGATIVE MAGNETORESISTANCE IN (,)

Conference Physical Phenomena at High Magnetic Fields IV · July 2002 Full text Cite

Contribution of the surface mechanism to sputtering of (001) Ni: molecular dynamics computer simulation studies

Journal Article Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms · January 1, 1999 We calculated the contribution to sputtering yield of atoms strongly blocked towards the surface normal during ejection, sputtered at final polar angles Ve less than initial polar ejection angles Vo, for Ar+ ion bombardment of (001) face of single crystal ... Full text Cite