High-Pressure Studies on Superconducting Iron-Based LaFeAsO_1-<i>x</i>F_<i>x</i>, LaFePO and SrFe₂As₂

Abstract

Electrical resistivity and magnetic susceptibility measurements under high pressure were performed on iron-based superconductor LaFePO and LaFeAsO 1- x F x system. A steep increase in superconducting transition temperature ( T c ) was observed for LaFePO and “optimum-doped” and “over-doped” LaFeAsO 1- x F x . Pressure-induced superconductivity was confirmed in undoped LaFeAsO and SrFe 2 As 2 by electrical resistivity measurements under high pressure. X-ray diffraction measurements were also performed under high pressure up to 10 GPa for LaFePO and LaFeAsO 1- x F x system, where the anisotropic decrease of the lattice constants was observed with applying pressure.