Pressure effect on superconducting properties of LaO1-xFxFeAs (x=0.11) superconductor

Diamagnetic susceptibility measurements under high hydrostatic pressure (up to 1.03 GPa) were carried out on a newly discovered Fe-based superconductor LaO1-xFxFeAs (x = 0.11). The transition temperature T-C, defined as a point at the maximum slope of superconducting transition, was enhanced almost linearly by hydrostatic pressure, yielding a dT(C)/dP of about 1.2 K GPa(-1). Differential diamagnetic susceptibility curves indicate that the underlying superconducting state is complicated. It is suggested that pressure plays an important role on pushing the low T-C superconducting phase toward the main (optimal) superconducting phase.