Magnetic properties of ultra thin epitaxial Fe films on GaAs(001)

Morton, S A ; Tobin, J G ; Spangenberg, M ; Neal, J R ; Shen, T H ; Waddill, G D ; Matthew, J D ; Greig, D ; Malins, A R ; Seddon, E A ; Hopkinson, M

Lawrence Livermore National Laboratory

关键词: Exchange Interactions;    Magnetic Properties;    Temperature Dependence;    Thickness;    37 Inorganic, Organic, Physical And Analytical Chemistry;   

DOI  :  10.2172/15009722
RP-ID  :  UCRL-TR-202074
RP-ID  :  W-7405-ENG-48
RP-ID  :  15009722

美国|英语

来源: UNT Digital Library

【 摘 要 】

The magnetic properties of epitaxial Fe films on GaAs in the range of the first few monolayers have been the subject of a considerable number of investigations in recent years. The absence of magnetic signatures at room temperature has been attributed to the existence of a magnetic ''dead'' layer as well as superparamagnetism. By examining the temperature dependence of the magnetic linear dichroism of the Fe core level photoelectrons, we found that these ''non-ferromagnetic'' layers had in fact a Curie temperature, T{sub c}, substantially lower than room temperature, e.g., a T{sub c} of about 240K for thin films of a nominal thickness of 0.9 nm. The values of Curie temperature were sensitive to the initial GaAs substrate conditions and the thickness of the Fe over-layer with a layer of thickness of 1.25 nm showing a T{sub c} above room temperature. The data suggest that the ultrathin Fe films on GaAs(001) are ferromagnetic, although a weaker exchange interaction in the films lead to a substantial reduction in Curie temperature.