High-pressure study on LaFeAs(O <sub>1−x</sub> F <sub>x</sub> ) and LaFeAsO <sub>δ</sub> with different T <sub>c</sub>
High-pressure study on LaFeAs(O <sub>1−x</sub> F <sub>x</sub> ) and LaFeAsO <sub>δ</sub> with different T <sub>c</sub>
We report studies on pressure dependence of superconducting transition temperature (Tc) of LaFeAsOδ (δ< 0.3), LaFeAs(O0.5F0.5) and LaFeAs(O0.89F0.11) samples. In situ resistance measurements under high pressure showed that the Tc of these three compounds increases with pressure initially, reaches a maximum value and then decreases with further increasing pressure, although …