The structural evolution and superconductivity under pressure for superconductor AFe₂As₂ (A = Ba, Sr)

In collinear antiferromagnetic (AFM) order, the structural evolution and electronic structure of AFe₂As₂ (A = Ba, Sr) under hydrostatic and uniaxial pressures have been studied. The Fe-Fe distance is closely related to the AFM suppression as well as the Fe-As bond. Through analysis of Fermi surface and band diagram, the uniaxial pressure along c-axis can make the band near the Γ point to produce Lifshitz transition under the condition of lower pressure, and it is easier to suppress Fe magnetic moment. If the pressure component along c-axis is larger in the experiment, it is easier to cause the superconducting. The superconductivity of BaFe₂As₂ and SrFe₂As₂ under pressure may be due to the increasing of Fe 3d- and As 4p-hybridized bands width near the Fermi level.