Uncompensated moments in antiferromagnets: Origin and role in exchange bias.

ORAL

Abstract

Exchange bias (EB) is a ferromagnet (FM) -- antiferromagnet (AF) proximity effect. The depth profile of the magnetization across the interface between a FM (Co) and an AF (FeF$_{2})$ in an EB system has been measured. [1] It was found that both uncompensated and compensated magnetic moments are present in FeF$_{2}$. The origin of these moments remains an open question. Our high-resolution STEM study confirms that FeF2 grows epitaxially on MgF$_{2}$, and its structural quality is very high. It also reveals that the substrate surface imperfections do not necessarily affect the quality of the FeF$_{2}$ layer. In magnetization measurements of just a thin film of FeF$_{2}$, without a FM, we find an uncompensated magnetization. This magnetization demonstrates temperature dependence and horizontal hysteresis loop shift, typical for EB. Dependence of this magnetization on the substrate, film parameters and cooling conditions will be discussed. Work supported by US DOE. \\ $[1]$ M. R. Fitzsimmons \textit{et al}., Phys. Rev. B \textbf{75}, 214412 (2007).

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Authors

  • Igor V. Roshchin

    • Physics Department, University of California, San Diego and Texas A\&M University

  • Zhi-Pan Li

    • Physics Department, University of California, San Diego and Cornell University

  • Casey W. Miller

    • Physics Department, University of California, San Diego and University of South Florida

  • Maria Varela

    • Oak Ridge National Laboratory

  • Stephen J. Pennycook

    • Oak Ridge National Laboratory

  • Ivan K. Schuller

    • Physics Department, University of California, San Diego