Electronic and magnetic properties of off-stoichiometric Co 2 Mn β Si /MgO interfaces studied by x-ray magnetic circular dichroism

V. R. Singh, V. K. Verma, K. Ishigami, G. Shibata, A. Fujimori, T. Koide, Y. Miura, M. Shirai, T. Ishikawa, G. F. Li, M. Yamamoto

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Abstract

We have studied the electronic and magnetic states of Co and Mn atoms at the interface of the Co 2 Mn β Si (CMS)/MgO (β = 0.69, 0.99, 1.15, and 1.29) magnetic tunnel junction (MTJ) by means of x-ray magnetic circular dichroism. In particular, the Mn composition (β) dependences of the Mn and Co magnetic moments were investigated. The experimental spin magnetic moments of Mn, m spin(Mn), derived from x-ray magnetic circular dichroism weakly decreased with increasing Mn composition β in going from Mn-deficient to Mn-rich CMS films. This behavior was explained by first-principles calculations based on the antisite-based site-specific formula unit (SSFU) composition model, which assumes the formation of only antisite defect, not vacancies, to accommodate off-stoichiometry. Furthermore, the experimental spin magnetic moments of Co, m spin(Co), also weakly decreased with increasing Mn composition. This behavior was consistently explained by the antisite-based SSFU model, in particular, by the decrease in the concentration of Co Mn antisites detrimental to the half-metallicity of CMS with increasing β. This finding is consistent with the higher tunnel magnetoresistance ratios which have been observed for CMS/MgO/CMS MTJs with Mn-rich CMS electrodes.

Original languageEnglish
Article number203901
JournalJournal of Applied Physics
Volume117
Issue number20
DOIs
Publication statusPublished - 2015 May 28

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Singh, V. R., Verma, V. K., Ishigami, K., Shibata, G., Fujimori, A., Koide, T., Miura, Y., Shirai, M., Ishikawa, T., Li, G. F., & Yamamoto, M. (2015). Electronic and magnetic properties of off-stoichiometric Co 2 Mn β Si /MgO interfaces studied by x-ray magnetic circular dichroism. Journal of Applied Physics, 117(20), [203901]. https://doi.org/10.1063/1.4921538