High-Pressure Studies on Superconductivity in LaFeAsO1−x F x and SmFeAsO1−x F x

Abstract

The pressure dependence on the superconducting transition temperature (Tc) was investigated for the iron-based superconductors LaFeAsO1−xFx and SmFeAsO1−xFx. The Tc’s increase largely for LaFeAsO1−xFx with a small increase of pressure, while a sharp decrease of Tc was observed for SmFeAsO1−xFx. The electrical resistivity measurements reveal pressure-induced superconductivity for undoped LaFeAsO and SmFeAsO. These pressure effects seem to be related to an anisotropic decrease of the lattice constants under high pressure from the x-ray diffraction measurements up to 10 GPa for the LaFeAsO1−xFx system.