Strong Damping‐Like Spin‐Orbit Torque and Tunable Dzyaloshinskii–Moriya Interaction Generated by Low‐Resistivity Pd _{1− x} Pt _x Alloys

Journal Article · Wed Feb 27 00:00:00 EST 2019 · Advanced Functional Materials

DOI:https://doi.org/10.1002/adfm.201805822· OSTI ID:1497240

Zhu, Lijun  ^[1]; Sobotkiewich, Kemal ^[2]; Ma, Xin ^[2]; Li, Xiaoqin ^[2]; Ralph, Daniel C. ^[3]; Buhrman, Robert A. ^[1]

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1. Cornell University Ithaca NY 14850 USA
2. Department of Physics Center for Complex Quantum Systems The University of Texas at Austin Austin TX 78712 USA
3. Cornell University Ithaca NY 14850 USA, Kavli Institute at Cornell Ithaca NY 14853 USA

Abstract Despite their great promise for providing a pathway for very efficient and fast manipulation of magnetization, spin‐orbit torque (SOT) operations are currently energy inefficient due to a low damping‐like SOT efficiency per unit current bias, and/or the very high resistivity of the spin Hall materials. This work reports an advantageous spin Hall material, Pd _{1− x} Pt _x , which combines a low resistivity with a giant spin Hall effect as evidenced with three independent SOT ferromagnetic detectors. The optimal Pd _0.25 Pt _0.75 alloy has a giant internal spin Hall ratio of >0.60 (damping‐like SOT efficiency of ≈0.26 for all three ferromagnets) and a low resistivity of ≈57.5 µΩ cm at a 4 nm thickness. Moreover, it is found that the Dzyaloshinskii–Moriya interaction (DMI), the key ingredient for the manipulation of chiral spin arrangements (e.g., magnetic skyrmions and chiral domain walls), is considerably strong at the Pd _{1− x} Pt _x /Fe _0.6 Co _0.2 B _0.2 interface when compared to that at Ta/Fe _0.6 Co _0.2 B _0.2 or W/Fe _0.6 Co _0.2 B _0.2 interfaces and can be tuned by a factor of 5 through control of the interfacial spin‐orbital coupling via the heavy metal composition. This work establishes a very effective spin current generator that combines a notably high energy efficiency with a very strong and tunable DMI for advanced chiral spintronics and spin torque applications.

• Sponsoring Organization: USDOE
• OSTI ID: 1497240
• Journal Information: Advanced Functional Materials, Journal Name: Advanced Functional Materials Vol. 29 Journal Issue: 16; ISSN 1616-301X
• Publisher: Wiley Blackwell (John Wiley & Sons)
• Country of Publication: Germany
• Language: English