Theoretical design of perpendicularly magnetized magnetic tunnel junctions on the basis of the tetragonal Heusler alloys

2015 Fiscal Year Final Research Report

• Project/Area Number: 25420281
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Electronic materials/Electric materials
• Research Institution: Kyoto Institute of Technology
• Principal Investigator: Miura Yoshio 京都工芸繊維大学, 電気電子工学系, 准教授 (10361198)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: スピントロニクス / 第一原理計算

Outline of Final Research Achievements

Magnetic materials with high perpendicular magneto-crystalline anisotropy (MCA) have great advantage in the reduction of the switching current . Among the magnetic materials with perpendicular MCA, D022-Mn3Ga alloys have attractive features, which are high perpendicular MCA (Ku>1.0 MJ/m3), the high Curie temperature (TC=730K) and the small saturation magnetization (MS=0.25μB/atom) due to the antiferromagnetic behavior. We investigated spin dependent transport properties of magnetic tunnel junctions (MTJs) with Mn3Ga or Mn3Ge using the first-principles calculations. We found that tunneling magntoresistance (TMR) ratios of Mn3Ga/MgO MTJs is very small, which is about 40% for MnGa termination. On the other hand, we obtained over 4000% TMR ratios both for MnMn and MnGe terminations of Mn3Ge-based MTJs due to the half-metallic electronic structure on the state. We concluded that Mn3Ge is a promising material providing large TMR effects as well as strong perpendicular magnetic anisotropy.

Free Research Field

磁性理論