Observation of a Low Curie Temperature Ferromagnetic Phase of Ultrathin Epitaxial Fe Films on GaAs(0 0 1)


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 a ferromagnetic regime with a Curie temperature, Tc substantially lower than room temperature, e.g., a Tc of about 240 K 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 Tc above room temperature. The data suggest that the thin Fe films on GaAs(0 0 1) may have ferromagnetic character at an earlier stage of growth than previously expected, although a weaker exchange interaction in the films leads to a substantial reduction in Curie temperature.




Engineering and Physical Sciences Research Council
Lawrence Livermore National Laboratory
United States. Department of Energy
University of California (System)

Keywords and Phrases

Curie Temperature; Core Level Photoelectrons; Epitaxial Fe/GaAs; Magnetic Linear Dichroism; Ultra Thin Magnetic Films

Document Type

Article - Conference proceedings

Document Version


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© 2005 Elsevier, All rights reserved.

Publication Date

01 Apr 2005