Indication of a non-magnetic surface layer on a magnetic single crystal

Abstract

The structural and electronic properties of the surfaces of Sm(0001) and Eu/Gd(0001) were studied by scanning tunneling microscopy and spectroscopy at temperatures between 10 and 110 K. In both systems, an unoccupied surface state is observed that exhibits a temperature-dependent splitting into two states for Eu/Gd(0001), while it is unsplit on Sm(0001). This strongly indicates that the divalent outermost surface layer of Sm(0001) is non-magnetic despite the antiferromagnetic trivalent Sm substrate. These findings open new opportunities for magnetic studies of ultra-thin Sm films.