Title

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

Abstract

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.

Department(s)

Physics

Sponsor(s)

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

Citation

File Type

text

Language(s)

English

Rights

© 2005 Elsevier, All rights reserved.

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