Electronic structure near Fermi level in few-layer films of FeSe

Abstract

The electronic density of states of one- and two-layer FeSe-thin films deposited on SrTiO3 was calculated using a Real Space Density Functional Theory method. This method has been previously used to calculate X-ray absorption near edge spectroscopy (XANES) and Resonant X-ray Inelastic Scattering (RIXS) in the system FeSe[Formula: see text]Te[Formula: see text], finding agreement with experimental spectra. In that system, we also found the same trend in the calculated density of states at the Fermi level and the behavior of T[Formula: see text] with varying Te content. In the present case, we find non-negligible contributions of Ti-3d states in the vicinity of the Fermi level, and qualitative differences in the density of states between calculations that assume antiferromagnetic order of the FeSe layers compared with those that assume non-magnetic order. In the magnetic-order calculation, we obtain the highest density of states for the one-layer system, compared with the two-layer or bulk FeSe. Such a trend does not correlate with the experimentally reported increase from T[Formula: see text]=8 K in bulk FeSe to T[Formula: see text]=65 K for one-layer FeSe, and absence of superconductivity in two-layer FeSe.