High Curie temperature in Eu-doped GaN caused by Ga-vacancies

ORAL

Abstract

The present study computationally demonstrates that room-temperature ferromagnetism, which has been experimentally observed in Eu-doped GaN, is induced by holes in N 2p states (i.e., Zener’s double exchange interaction) that arise on the assumption that Ga vacancies appear as a result of the introduction of Eu ions (i.e., volume compensation). The calculated Curie temperature (TC) suddenly increases over a certain range of Ga vacancy concentrations and gradually increases with increasing concentration of Eu ions. High TC above room temperature is dominated by Zener’s double exchange mechanism in partially occupied N 2p hole-states which itinerate throughout the whole crystals, and low TC is dominated by Zener’s p-f exchange mechanism in Eu 4f and N 2p hybridization. We can explain reasonably a surprising experimental data of 4000 μB per Gd atom in Gd-doped GaN reported by Dhar et al. [S. Dhar et al., Phys. Rev. Lett. 94, 037205 (2005)]

*This work is supported by JST-CREST (JPMJCR1777), JSPS-KAKENHI (18K04926 and 18H05212), and SpiN-RNJ.

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Presenters

  • Akira Masago

    • Graduate School of Engineering Science, Osaka University
    • Center for spintronics research network (CSRN), Osaka University
    • Osaka University

Authors

  • Akira Masago

    • Graduate School of Engineering Science, Osaka University
    • Center for spintronics research network (CSRN), Osaka University
    • Osaka University

  • Hikari Shinya

    • Research Institute of Electrical Communication, Tohoku University
    • Tohoku University

  • Tetsuya Fukushima

    • The Institute of Solid State Physics, The University of Tokyo
    • Institute for Solid State Physics, University of Tokyo
    • The University of Tokyo

  • Kazunori Sato

    • Graduate School of Engineering, Osaka University
    • Division of Materials and Manufacturing Science, Osaka University
    • Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University
    • Osaka University

  • Hiroshi Katayama-Yoshida

    • Graduate School of Engineering, The University of Tokyo
    • The Univesity of Tokyo
    • The University of Tokyo