Evolution of the hyperfine parameters of Fe in superconducting LiFeAs as observed by ~(57)Fe M?ssbauer spectroscopy

摘要

The LiFeAs superconductor is studied by ~(57)Fe M?ssbauer spectroscopy to detect possible changes in the hyperfine parameters in terms of temperature upon passing the superconductivity-transition-temperature at ～16 K. With decreasing temperature, a rather fast growth of spectral area and isomer shift below Tc, peaking at ～6 K was seen. This indicates an increase in the stiffness of the lattice followed by softening.