Wednesday, July 25, 2012

1110.2401 (Yoshio Inoue et al.)

Impurity-Induced Electronic Nematic State in Iron-Pnictide
Superconductors
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Yoshio Inoue, Youichi Yamakawa, Hiroshi Kontani
We propose that impurity-induced electronic nematic state is realized above the orthorhombic structure transition temperature $T_S$ in iron-pnictide superconductors. In the presence of strong orbital fluctuations near $T_S$, it is theoretically revealed that a single impurity induces non-local orbital order with $C_2$-symmetry, consistently with recent STM/STS measurements. Each impurity-induced $C_2$ orbital order aligns along a-axis by applying tiny uniaxial pressure along b-axis. In this impurity-induced nematic phase, the resistivity shows sizable in-plane anisotropy ($\rho_b/\rho_a \sim 2$) even above $T_S$, actually observed in various "detwinned" samples. The present study indicates the existence of strong orbital fluctuations in iron-pnictide superconductors.
View original: http://arxiv.org/abs/1110.2401

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