Large spin Hall effect in 300 °C annealed BiSb topological insulator and perpendicularly magnetized CoFeB using oxide buffer/seed and interfacial layers on Si/SiO2 substrates

Abstract

The application of topological insulator bismuth antimony (BiSb) to spin–orbit torque (SOT)–magnetic random-access memory (MRAM) applications using complementary metal–oxide–semiconductor process demands a high temperature exceeding its melting point. Here, we report an oxide-material engineering solution for sputtered BiSb and CoFeB/MgO junctions on an amorphous Si/SiO2 substrate that can withstand a 300 °C annealing temperature. By utilizing TiOx/TaOx buffer/seed layers and TaOx interfacial layer to protect BiSb during 300 °C annealing, we achieved a large spin Hall angle of 11.1 for BiSb and a strong perpendicular magnetic anisotropy for CoFeB/MgO. Our results provide a viable path toward high-performance BiSb-based SOT–MRAM.