Current-induced Magnetization Switching in Ferromagnetic Heusler Alloy Co2MnAl-based Magnetic Trilayers

Spin-orbit torque (SOT) has emerged as a promising candidate for efficient magnetization manipulation of spintronic devices in the past decade [1]. In the request for high SOT efficiency, various materials and mechanisms have been explored. Recently, researchers have found ferromagnet (FM) as a high-efficiency spin source to achieve current-induced magnetization switching in the FM/Ti/FM trilayers [2,3]. In this regard, FM Heusler alloy Co2MnAl (CMA), a predicted Weyl semimetal [4] with strong anomalous Hall effect (AHE), anomalous Nernst effect and Spin Hall effect [5-7], shows great potential for SOT application. Here, current-induced magnetization switching is realized in a multilayer CMA/Ti/CoFeB(CFB)/MgO. The perpendicularly-magnetized CFB layer serves as a spin-current analyzer. The Ti spacer layer is deployed to decouple the ferromagnetic layers and to develop perpendicular magnetic anisotropy of CFB, but allows efficient spin current transmission [2,8]. The switching current density is 1.362 and 1.905 × 107 A/cm2 for ordered and disordered CMA, respectively. Furthermore, the spin Hall efficiency ξ has been determined to be -0.072 and -0.029 via the current-induced AHE hysteresis loop shift technique for the ordered and disordered CMA. The ξ of ordered CMA is larger than that of Ta, CFB and NiFe [2]. At last, we attribute the low switching current density and enhanced spin Hall efficiency to the increase of spin-orbit interaction strength with the ordered structure.

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