Sunday, May 19, 2013

1305.3744 (Shigeyuki Ishida et al.)

Effect of doping on the magnetostructural ordered phase of iron
arsenides: A comparative study of the resistivity anisotropy in the doped
BaFe$_2$As$_2$ with doping into three different sites

Shigeyuki Ishida, Masamichi Nakajima, Tian Liang, Kunihiro Kihou, Chul-Ho Lee, Akira Iyo, Hiroshi Eisaki, Teruhisa Kakeshita, Yasuhide Tomioka, Toshimitsu Ito, Shin-ichi Uchida
In order to unravel a role of doping in the iron-based superconductors, we investigated the in-plane resistivity for BaFe$_2$As$_2$ doped at either of the three different lattice sites, Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, BaFe$_2$(As$_{1-x}$P$_x$)$_2$, and Ba$_{1-x}$K$_x$Fe$_2$As$_2$, focusing on the doping effect in the low-temperature antiferromagnetic/orthorhombic (AFO) phase. A major role of doping in the high-temperature paramagnetic/tetragonal (PT) phase is known to change the Fermi surface by supplying charge carriers or by exerting chemical pressure. In the AFO phase, we found a clear correlation between the magnitude of residual resistivity and resistivity anisotropy. This indicates that the resistivity anisotropy originates from the anisotropic impurity scattering from dopant atoms. The magnitude of residual resistivity is also found to be a parameter controlling the suppression rate of AFO ordering temperature $T_s$. Therefore, the dominant role of doping in the AFO phase is to introduce disorder to the system, distinct from that in the PT phase.
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