Hisashi Kotegawa, Yusuke Tomita, Hideki Tou, Hiroki Izawa, Yoshikazu Mizuguchi, Osuke Miura, Satoshi Demura, Keita Deguchi, Yoshihiko Takano
We report the electrical resistivity measurements under pressure for recently discovered BiS$_2$-based layered superconductors, Bi$_4$O$_4$S$_3$ and La(O,F)BiS$_2$. In Bi$_4$O$_4$S$_3$, the transition temperature $T_c$ decreases monotonously without distinct change in the metallic behavior in the normal state. In La(O,F)BiS$_2$, on the other hand, $T_c$ initially increases as increasing pressure, and then decreases above $\sim1$ GPa. The semiconducting behavior in the normal state is suppressed drastically and monotonously, whereas the evolution of $T_c$ is nonlinear. The strong suppression of the semiconducting behavior without doping in La(O,F)BiS$_2$ suggests that the Fermi surface is located in the vicinity of some instability. The present study elucidates that the superconductivity in BiS$_2$ layer favors the Fermi surface in the boundary between the semiconducting and the metallic behavior.
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http://arxiv.org/abs/1207.6935
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