Room temperature field-free switching of perpendicular magnetization through spin-orbit torque originating from low-symmetry type II Weyl semimetal

Abstract

Spin-orbit torque (SOT) is a promising strategy to deterministically switch the perpendicular magnetization, but usually requires an in-plane magnetic field for breaking the mirror symmetry, which is not suitable for most advanced industrial applications. Van der Waals (vdW) materials with low crystalline symmetry and topological band structures, e.g., Weyl semimetals (WSMs), potentially serve as an outstanding system that may simultaneously realize field-free switching and high energy efficiency. Yet, the demonstration of these superiorities at room temperature has not been realized. Here, we achieve a field-free switching of perpendicular magnetization by using a layered type II WSM, TaIrTe 4 , in a TaIrTe 4 /Ti/CoFeB system at room temperature with the critical switching current density ~2.4 × 10 6 A cm −2 . The field-free switching is ascribed to the out-of-plane SOT allowed by the low crystal symmetry. Our work suggests that using low-symmetry materials to generate SOT is a promising route for the manipulation of perpendicular magnetization at room temperature.

Impact of Technology Scaling and Back-End-of-the-Line Technology Solutions on Magnetic Random-Access Memories

“…SOT efficiency can be improved to reduce the write current requirement. Low symmetry SOT materials [35] with out of plane spin torque can enable field-free PMA switching and can also help reducing write current/energy. Magnetic material optimization to improve the WER slope is another promising path as it can lower the write delay and energy.…”

Magnetization switching driven by spin-orbit torque of Weyl semimetal WTe₂

“…物 理 学 此外, 它还实现了室温下零磁场高效的磁化翻转的 电调控 [65,66] . 这些发现将促进外尔半金属材料在下 一代高性能自旋电子器件的发展, 我们期望基于外 尔半金属的SOT器件未来能够得到广泛应用.…”

Spintronics with two-dimensional materials and van der Waals heterostructures

“…On the theoretical side, advances have revealed novel features unique to 2DMs [32][33][34][35], whereas experiments have started to produce significant torque efficiencies, which will serve as basis for further development [36][37][38][39]. Layered materials such as WTe 2 [40][41][42][43] or TaIrTe 4 [44,45] with reduced symmetries are also generating unconventional spin-orbit torques.…”