Spectroscopic evidence of two-dimensional character of the 90 K Bi 2(Sr,La,Ca)3Cu2O8 superconductors

Polarization-dependent angle-resolved photoemission experiments in the constant final state mode (absorption measurements) were performed on single crystals of the Bi-based 2212 material using synchrotron radiation in the photon energy range 10-40 eV. Evidence of polarization-dependent transitions due to Bi 5d→6p, Sr 4p→4d, and Ca 3p→3d excitations is observed. The data show that the electronic charge is highly localized to the layers of the crystal structure, thus providing a direct spectroscopic confirmation of the two-dimensional nature of these types of materials. Polarization-sensitive absorption signals at 14-15 eV attributed to Bi 6s→6p transitions show that the density of states (DOS) of the Bi 6pz holes peaks at about 0.7 eV higher energy than the DOS of the Bi 6px,y holes.

Duke Scholars

Author David Mitzi Thomas Lord Department of Mechanical Engineering and Materia ...