Electronic property of SrFe2As2 under high pressure studied by 57Fe Mössbauer spectroscopy

We have studied the electronic state of Fe atoms in SrFe2As2 under pressure at room temperature by 57Fe Mössbauer spectroscopy using a single crystalline sample. A center shift δc.s. and an electric quadrupole interaction parameter e2qQ/2 show the discontinuous increase and decrease at around 7 GPa,respectively, implying the pressure-induced structural phase transition. Furthermore, δc.s. deviates from the linear pressure dependence above 4 GPa without any anomaly in the pressure dependence of e2qQ/2. The anomaly corresponds to a change of the pressure dependence of lattice parameter ratio c/a, where volume of the unit cell decreases monotonously with increasing pressure.