Publication Date:
2015-05-23
Description:
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.
Print ISSN:
0021-8979
Electronic ISSN:
1089-7550
Topics:
Physics
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