Effects of off-stoichiometry on the spin polarization at the Co 2Mn βGe 0.38/MgO interfaces: X-ray magnetic circular dichroism study

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

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Abstract

We have studied the electronic and magnetic states of Mn and Co atoms at the Co 2Mn βGe 0.38 (CMG)/MgO (β=0.67-1.8) interfaces, which constitute CMG/MgO/CMG magnetic tunnel junctions, by means of x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroisms (XMCDs) at the Mn and Co L 2,3 edges and compared the deduced Co and Mn magnetic moments by the density-functional calculations with the coherent potential approximation (CPA). As the Mn content β increased, the intensity of Mn L 2,3 XMCD decreased, in agreement with the result of the CPA calculation, which showed the resultant reduction of charges and spin moment on Mn atoms because of the delocalization of Mn 3d electrons with increasing β. The Co spin magnetic moment for all the samples increased with decreasing β, again consistent with the present calculation and the previous density-functional calculation by Picozzi that the Co Mn antisite has a larger magnetic moment than that of Co atoms at the regular sites and reduces the spin polarization at the Fermi level and hence the tunnel magnetoresistance ratio.

Original languageEnglish
Article number144412
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume86
Issue number14
DOIs
Publication statusPublished - 2012 Oct 19

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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