Magnetic properties of Fe$_{1-y}$Co$_y$Si near insulator-metal transition

ORAL

Abstract

FeSi is a nonmagnetic narrow gap insulator with interesting temperature-dependent magnetic and optical properties. When doped with Mn, holes are introduced to the FeSi system along with S=1 magnetic moments. As a result, a non-Fermi liquid metallic state is observed due to the underscreening of the S=1 moments. Here we investigate the effects of Co doping of FeSi (Fe$_{1-y}$Co$_y$Si, 0$\leq$y$\leq$0.03) to explore the insulator-to-metal transition and to compare with Mn-doped effects. We find a systematic increase of the Curie constant and Weiss temperature of the impurity-induced low temperature susceptibility with y. The Curie constant and saturated magnetization indicates that there is an underlying competition between screening of the magnetic moments at low y and ferromagnetic ordering at higher Co-concentrations. Transport measurements are underway to explore the associated charge carrier properties in this semiconducting system on the verge of ferromagnetism.

*This work is supported by NSF DMR.

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Authors

  • Yan Wu

    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803
    • Louisiana State University

  • Bradford Fulfer

    • Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803

  • Julia Chan

    • Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803

  • David Young

    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803

  • John DiTusa

    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803