AC magnetic measurement of LiFeAs at pressures up to 5.2 GPa: The relation between T c and the structural parameters

The pressure effects on the 111-type Fe-based superconductor LiFeAs were investigated through AC susceptibility measurements and X-ray diffraction experiments, and revealed a correlation between the superconducting transition temperature (T c ) and the As-Fe-As bond angle (α) rather than the height of As from the Fe layers (h As). As the pressure was increased, T c of 17 K at P = 0 GPa decreased down to 10 K at P = 5.2 GPa. According to a previous report from an X-ray diffraction experiment, α changes from 101.5° at 0 GPa to 97.8° at 17 GPa. The obtained change in T c is consistent with Lee et al.’s plot of T c as a function of α, and from this result, we conclude that T c will fall to zero at around α = 98°.