Spectral evolution in an insulator exhibiting linear specific heat

Abstract

We investigate the spectral evolution of an antiferromagnetic insulator, La$_{0.2}$Sr$_{0.8}$MnO$_3$ exhibiting linear specific heat using state-of-the-art high resolution photoemission spectroscopy. Experimental spectral functions exhibit Fermi liquid like energy dependence at all the temperatures studied. Room temperature spectrum possess finite density of states at the Fermi level that vanishes generating a soft gap at about 260 K (the magnetic transition temperature). High resolution spectra reveal a hard gap in the magnetically ordered phase (C-type antiferromagnet). These results indicate signature of an amorphous phase coexisting with the long range ordered phase in these materials.