Properties of molecular beam epitaxy grown Eu_x(transition metal)_y films (transition metals: Mn, Cr)

摘要

The electronic and crystallographie structures, as well as the magnetic properties, of Eu_x(transition metal)_y (transition metals: Mn, Cr) thin films grown by molecular beam epitaxy were studied. Relative changes of the Eu/Mn and Eu/Cr ratios derived from the XPS lines, as well as x-ray reflectivity, indicate mixing of the Eu/Mn and Eu/Cr layers. Valency transitions from Eu~(2+) to Eu~(3+) were observed in both systems for most studied stoichiometries. A transition to a magnetically ordered phase was observed at 15 K, 40 K, and 62 K for selected films in the Eu-Mn system, and at 50 K for the film with a Eu/Cr ratio of 0.5.