Electron-phonon coupling enhancement and displacive magnetostructural transition in SrCr2 As2 under magneto-Raman spectroscopy.

Abstract

A Raman spectroscopy study on high quality single crystals of SrCr2 As2 (SCA) in the temperature T range 4\xa0K < T < 300\xa0K and high applied magnetic fields up to H = 9\xa0T is presented. The chromium B 1g phonon analysis reveals two anomalous shifts in the frequency, the first below T = 250\xa0K at H = 0\xa0T in the saturated AFM G-type order likely due to an enhanced electron-phonon coupling by the magnetic order, whereas the second anomaly occurs above H = 4\xa0T at T = 4\xa0K likely as a consequence of a magnetostructural displacive transition. Renormalization of the electronic Raman spectra in both studies reveals a decrease in the electronic density of states with decreasing T and increasing H, respectively, with consequent changes in the Fermi surface, which are intrinsically related to the observed anomalies.