講演情報
[16p-S4_201-16]Large Spin-Orbit Torque Induced by Highly Textured BiSb(012) Topological Insulator Deposited on Si/SiO_2 Substrates Using Oxide Buffer/Seed Stack
〇(M2)Wentao Li1, Hoang Huy Ho1, Xiaokun Yan1, Van Thuan Pham1, Shigeyuki Hirayama2, Yushi Kato2, Nam Hai Pham1 (1.Science Tokyo, 2.Samsung Japan Corp.)
キーワード：
Topological Insulator、SOT MRAM、BiSb
BiSb is a promising spin-orbit torque (SOT) material for SOT-MRAM due to its large spin Hall effect and high electrical conductivity, but high-quality BiSb films have mainly been realized on single-crystal substrates. For Si/SiO2 integration, we target the BiSb(012) orientation, which hosts multiple Dirac cones and is expected to yield a large spin Hall angle. We demonstrate highly textured BiSb(012) grown on amorphous Si/SiO2 by employing an oxide buffer/seed stack TiOx(4 nm)/MgO(2 nm) with a Ta wetting layer, followed by Bi90Sb10(10 nm) and a perpendicular CoFeB/MgO stack to suppress shunting currents. XRD and AFM confirm strong (012) texture and low surface roughness. Second-harmonic Hall measurements indicate a large effective spin Hall angle of 11.6. Current-pulse switching of CoFeB is achieved with a threshold current density of 4.8 MA/cm2 at 50 us pulse width, about one order of magnitude lower than typical heavy metals. This oxide-based integration route enables low-power BiSb SOT devices on Si/SiO2 substrates.