Effect of metallic Mg insertion on the magnetoresistance effect in MgO-based tunnel junctions using D022-Mn3-δGa perpendicularly magnetized spin polarizer

Takahide Kubota, Shigemi Mizukami, Daisuke Watanabe, Feng Wu, Xianmin Zhang, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

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26 Citations (Scopus)

Abstract

Effects of metallic Mg insertion on tunnel magnetoresistance (TMR) effect were investigated in D022-Mn2.4Ga/Mg/MgO/CoFe magnetic tunnel junctions (MTJs). The thickness of Mg (dMg) was varied from 0 to 1.4 nm. TMR ratio exhibited maximum value of 22% with the dMg =0.4 nm and a negative value of 14% with the dMg =1.4 nm at 10 K. The dependence of resistance area products (R ×A) on the dMg showed similar trend compared with those of what reported in conventional CoFeB-MgO based MTJs. Bias voltage dependences of differential conductance (dI/dV) and TMR ratio exhibited asymmetry with respect to the zero-bias. The difference of the zero-bias anomaly in the dI/dV spectra was also discussed, and an indication of reducing the inelastic tunneling process was found, implying the improvement of barrier/magnetic-layer interfaces by the Mg insertion. Considering a theoretical work done by Wang Phys. Rev. B 82, 054405 (2010), the inversion of the sign and the asymmetric bias voltage dependence of TMR ratio were inferred to be attributed to the minority spin tunneling via a quantum well state in the thin metallic Mg layer between Mn2.4Ga and MgO.

Original languageEnglish
Article number013915
JournalJournal of Applied Physics
Volume110
Issue number1
DOIs
Publication statusPublished - 2011 Jul 1

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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