Presentation Information
[16p-S2_201-7]Comparison of spin Hall angles of BiSb topological insulator measured by spin accumulation, spin–orbit torque, and spin Hall magnetoresistance
〇(D)MIN LIU1, Ruixian Zhang1, Quang Le2, Brian York2, Cherngye Hwang2, Xiaoyong Liu2, Xiaoyu Xu2, Son Le2, Maki Maeda3, Tuo Fan3, Yu Tao3, Hisashi Takano3, Pham Nam Hai1 (1.Institute of Science Tokyo, 2.W Digital Inc., G.O., 3.W Digital Inc., F.)
Keywords:
spintronics,spin Hall angle,topological insulator
The spin Hall angle is a primary parameter characterizing the charge–spin conversion efficiency in spintronic materials and is critical for both spin–orbit torque (SOT) MRAM and magnetic sensors. The BiSb topological insulator is of particular interest due to its giant topological surface-state–driven spin Hall effect1), enabling ultra-low-power operation beyond conventional heavy metals. However, spin Hall angle extracted by different techniques often varies by orders of magnitude,2) making direct comparison essential for understanding the underlying physics and device implementation. In this work, we systematically investigate spin Hall angle of BiSb/interlayer/CoFe heterostructures using three complementary approaches: (i) spin accumulation in a pillar device, (ii) second orbit torque, and (iii) spin Hall magnetoresistance in a Hall bar device. Here, SA detects interfacial spin accumulation on the interface of BiSb, while SMR probes spin-reflection and SOT probes spin-transfer induced by spin absorption into the FM layer. Spin Hall angle obtained from all methods increases at low temperatures, consistent with the surface-state-driven spin Hall effect in BiSb. We observed that exhibits the largest magnitude and strongest temperature dependence, whereas and remain smaller. We attributed these differences to the different physics beyond these techniques: SOT and SMR measure the spin-transfer/spin reflection at the interlayer/FM interface and thus depend on the details of the spin transport across the interlayer and at the interlayer/FM interface. Meanwhile, SA can measure the spin Hall angle under the spin-current open circuit. Our results demonstrate that SA is a useful method for probing the intrinsic value of the spin Hall angle.3)