Pressure tuning of the iron-based superconductor (Ca0.73La0.27)FeAs2

Abstract

Pressure is an efficient tool to tune the electronic structure of iron-based superconductors. Here, we performed systematic high pressure transport and magnetization measurements on (Ca0.73La0.27)FeAs2 single crystal samples. Filamentary superconductivity is induced under a small applied pressure P=1.6 GPa. At P=3.2 GPa, the superconductivity becomes bulk. It is found that Tc increases initially and then decreases with further increasing pressure, forming a dome shape. Hall resistivity is measured simultaneously and the Hall coefficient RH at 50 K shows nonmonotonic dependence on pressure. In addition, RH reverse sign at a critical pressure Pc=3.9 GPa, where Tc reaches the maximum and there is a sudden increase in superconducting diamagnetism. Theoretical calculation results show a pressure induced Lifshitz transition of the Fermi surface which might be responsible for the appearance of superconductivity. © 2021 American Physical Society.