Effect of Iodine Doping on Bi$_{2}$Sr$_{2}$Ca$_{1}$Cu$_{2}$O$_{x}$: Charge Transfer or Interlayer Coupling?

TL;DR

This study compares iodine-doped and oxygen-annealed Bi-2212 single crystals, revealing that iodine doping primarily modifies interlayer coupling rather than hole concentration, affecting the electronic structure and superconducting transition temperature.

Contribution

It demonstrates that iodine doping alters interlayer coupling in Bi-2212, not the hole concentration, providing insight into the doping mechanism's effect on electronic structure.

Findings

Iodine doping reduces T_c slightly compared to oxygen annealing.

Hole concentration remains unchanged between iodine-doped and oxygen-annealed samples.

Iodine intercalation significantly affects the electronic structure near the Fermi level.

Abstract

A comparative study has been made of iodine-intercalated Bi$_{2}$Sr$_{2}$Ca$_{1}$Cu$_{2}$O$_{x}$ single crystal and 1 atm O$_{2}$ annealed Bi$_{2}$Sr$_{2}$Ca$_{1}$Cu$_{1}$O$_{x}$ single crystal using AC susceptibility measurement, X-ray photoemission (XPS) and angle-resolved ultraviolet photoemission spectroscopy (ARUPS). AC susceptibility measurement indicates that O$_{2}$-doped samples studied have T$_{c}$ of 84 $^{o}$K, whereas T$_{c}$ of Iodine-doped samples studied are 80 $^{o}$K. XPS Cu 2p core level data establish that the hole concentration in the CuO$_{2}$ planes are essentially the same for these two kinds of samples. ARUPS measurements show that electronic structure of the normal states near the Fermi level has been strongly affected by iodine intercalation. We conclude that the dominant effect of iodine doping is to alter the interlayer coupling.