Continuous Tuning of the Magnitude and Direction of Spin‐Orbit Torque Using Bilayer Heavy Metals. (4th August 2016)

• Record Type: Journal Article
• Authors: He, Pan; Qiu, Xuepeng; Zhang, Vanessa L.; Wu, Yang; Kuok, Meng Hau; Yang, Hyunsoo
• Is Part Of: Advanced Electronic Materials. Volume 2:Number 9(2016)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2016-08-04
• Subjects: current‐induced magnetization switching -- Dzyaloshinskii–Moriya interaction -- spin‐orbit fields -- spin‐orbit torques -- spintronics; Materials -- Electric properties -- Periodicals; Materials science -- Periodicals; Magnetic materials -- Periodicals; Electronic apparatus and appliances -- Periodicals; 537
• DOI: 10.1002/aelm.201600210
• Languages: English
• ISSNs: 2199-160X

Abstract

Abstract : Spin‐orbit torques (SOTs) have opened a new path to switch the magnetization in perpendicularly magnetized films and are of great interest due to their potential applications in novel data storage technology, such as magnetic random access memory (MRAM). The effective manipulation of SOT has thus become an important step toward these applications. Here, current‐induced spin‐orbit effective fields and magnetization switching are investigated in Pt/Ta/CoFeB/MgO structures with bilayer heavy metals. With a fixed thickness (1 nm) of the Ta layer, the magnitude and sign of current‐induced spin‐orbit effective fields can be continuously tuned by changing the Pt layer thickness, consistent with the current‐induced magnetization switching data. The ratio of longitudinal to transverse spin‐orbit effective fields is found to be determined by the Ta/CoFeB interface and can be continuously tuned by changing the Pt layer thickness. The Dzyaloshinskii–Moriya interaction (DMI) is found to be weak and shows an insignificant variation with the Pt thickness. The results demonstrate an effective method to tune SOTs utilizing bilayer heavy metals without affecting the DMI, a desirable feature which will be useful for the design of SOT‐based devices. Abstract : Continuous tuning of the magnitude and direction of spin‐orbit torque is achieved by using bilayer heavy metals, which is consistent with current‐induced magnetization switching efficiency. Bilayer heavy metals are demonstrated as an effective system to tune the spin‐orbit torque and Dzyaloshinskii–Moriya interaction separately and provide further insights into the origin of spin‐orbit effective fields.