LaO as a candidate substrate for realizing superconductivity in an FeSe epitaxial film

Abstract

The significantly enhanced superconducting transition temperature (Tc) of an FeSe monolayer on SrTiO3(001) substrate has attracted extensive attention in recent years. Here, based on firstprinciples electronic structure calculations, we propose another candidate substrate LaO(001) for the epitaxial growth of FeSe monolayer to realize superconductivity. Our calculations show that for the optimal adsorption structure of FeSe monolayer on LaO(001), the stripe antiferromagnetic state and the dimer antiferromagnetic state are almost energetically degenerate, indicating the existence of strong magnetic fluctuation that is beneficial to the appearance of superconductivity. According to the Bader charge analysis, the calculated electron doping from the LaO substrate to the FeSe monolayer is about 0.18 electrons per Fe atom, even larger than that in case of FeSe/SrTiO3(001). Since LaO was also reported to be a superconductor with Tc ∼ 5 K, it may have a superconducting proximity effect on the epitaxial FeSe film and vice versa. These results suggest that LaO would be an interesting substrate to study the interface-related superconductivity.

First-principles study of the superconductivity in LaO

“…Interestingly, our calculations also suggest that the superconductivity (T c ∼ 1.4 K) still exists when the LaO film is reduced to trilayer thickness. Our works call for more effort to explore superconductivity in rare-earth compounds and their stacking structures 60 as well as to study the related superconducting mechanism.…”