Lattice Softening in Metastable bcc CoxMn100 - X (001) Ferromagnetic Layers for a Strain-Free Magnetic Tunnel Junction

Kevin Elphick, Kenta Yoshida, Tufan Roy, Tomohiro Ichinose, Kazuma Kunimatsu, Tomoki Tsuchiya, Kazuya Z. Suzuki, Masahito Tsujikawa, Yasuyoshi Nagai, Shigemi Mizukami, Masafumi Shirai, Atsufumi Hirohata

Research output: Contribution to journalArticlepeer-review

Abstract

In spintronics, one of the long-standing questions is why the MgO-based magnetic tunnel junction (MTJ) is almost the only option for achieving a large tunneling magnetoresistance (TMR) ratio at room temperature, although this is not as large as the theoretical prediction. This study focuses on the development of an almost strain-free MTJ using metastable bcc CoxMn100-x (Co-Mn) ferromagnetic films. We investigate the degree of crystallization in MTJs consisting of Co-Mn/MgO/Co-Mn in relation to their TMR ratios. Cross-section high resolution transmission electron microscopy reveals that almost consistent lattice constants of these layers for 66 ≤ x ≤ 83 with large TMR ratios of 229% at room temperature, confirming the soft nature of the Co-Mn layer with some dislocations at the MgO/Co75Mn25 interfaces. Ab initio calculations confirm the crystalline deformation stability across a broad compositional range in Co-Mn, proving the advantage of a strain-free interface for much larger TMR ratios.

Original languageEnglish
Article number054052
JournalPhysical Review Applied
Volume16
Issue number5
DOIs
Publication statusPublished - 2021 Nov

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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