Spectral evolution in an insulator exhibiting linear specific heat

Abstract

In this work, we investigate, using state-of-the-art high-resolution photoemission spectroscopy, the spectral evolution of an antiferromagnetic insulator, La_0.2Sr_0.8MnO₃, exhibiting linear specific heat. Experimental spectral functions exhibited Fermi liquid-like energy dependence at all the temperatures studied. Room temperature spectra possess finite density of states at the Fermi level that vanishes, generating a soft gap at about 265 K (the magnetic transition temperature). High-resolution spectra reveal a hard gap in the magnetically ordered phase (C-type antiferromagnet). These results indicate the signature of an amorphous phase, presumably magnetic in nature, coexisting with the long-range ordered phase in these materials.