Indication of a nonmagnetic surface layer on a magnetic single crystal

Wegner D, Kaindl G

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 nonmagnetic despite the antiferromagnetic trivalent Sm substrate. These findings open opportunities for magnetic studies of ultrathin Sm films.