First-principles study of spin-transfer torque in Co2MnSi/Al/Co2MnSi spin-valve

TL;DR

This first-principles study investigates spin-transfer torque in Co2MnSi/Al/Co2MnSi spin-valves, revealing how interface quality affects efficiency and suggesting high potential for magnetic switching applications.

Contribution

The paper provides a detailed first-principles analysis of STT in Co2MnSi-based spin-valves, highlighting effects of interface disorder and comparing different interface structures.

Findings

Clean CoCo/Al interface shows more skewed angular dependence of STT.

Interfacial disorder reduces differences in in-plane torkance between CoCo/Al and MnSi/Al.

CMS/Al/CMS system exhibits high efficiency in magnetic switching.

Abstract

The spin-transfer torque (STT) in Co2MnSi(CMS)/Al/Co2MnSi spin-valve system with and without interfacial disorder is studied by a first-principles noncollinear wave-function-matching method. It is shown that in the case of clean interface the angular dependence of STT for CoCo/Al (the asymmetry parameter Lambda approx. 4.5) is more skewed than that for MnSi/Al (Lambda approx. 2.9), which suggests the clean CoCo/Al architecture is much more efficient for the application on radio frequency oscillation. We also find that even with interfacial disorder the spin-valve of half-metallic CMS still has a relatively large parameter Lambda compared to that of conventional ferromagnet. In addition, for clean interface the in-plane torkance of MnSi/Al is about twice as large as that of CoCo/Al. However, as long as the degree of interfacial disorder is sufficiently large, the CoCo/Al and MnSi/Al will show approximately the same magnitude of in-plane torkance. Furthermore, our results demonstrate that CMS/Al/CMS system has very high efficiency of STT to switch the magnetic layer of spin-valve.