Orbit-Transfer Torque Driven Field-Free Switching of Perpendicular Magnetization

Abstract

The reversal of perpendicular magnetization (PM) by electric control is crucial for high-density integration of low-power magnetic random-access memory. Although the spin-transfer torque and spin-orbit torque technologies have been used to switch the magnetization of a free layer with perpendicular magnetic anisotropy, the former has limited endurance because of the high current density directly through the junction, while the latter requires an external magnetic field or unconventional configuration to break the symmetry. Here we propose and realize the orbit-transfer torque (OTT), that is, exerting torque on the magnetization using the orbital magnetic moments, and thus demonstrate a new strategy for current-driven PM reversal without external magnetic field. The perpendicular polarization of orbital magnetic moments is generated by a direct current in a few-layer WTe2 due to the existence of nonzero Berry curvature dipole, and the polarization direction can be switched by changing the current polarity. Guided by this principle, we construct the WTe2/Fe3GeTe2 heterostructures to achieve the OTT driven field-free deterministic switching of PM.

Multi-functional switch effect in interlocking molecular rotators-on-graphene systems using electric fields

“…A constant temperature (300 K) has been considered to the leads in order to ensure the stability of the structure. 60,61 The convergence criterion of the total energy is set to 10 À6 eV. At least 25 Å of the vacuum layer is used to avoid spurious interactions between periodic images.…”

Integrated Memory Devices Based on 2D Materials

“…used topological semimetal WTe 2 to construct Fe 3 GeTe 2 /WTe 2 heterostructures to implement all-vdW SOT switching, [126][127][128] as shown in Figure 9c. The switching current density (i.e., ≈3.9 × 10 10 A m −2 at 150 K) was one order of magnitude smaller than that of Fe 3 GeTe 2 /Pt, which was ascribed to the improved spin transparency across the sharp vdW interface.…”

Enhancing Spin–Orbit Torque Efficiency via Optimizing Pt‐Based Multilayers

“…In the past several years, numerous spin Hall materials have been investigated. [ 11–16 ] In particular, the typical HM Pt, which possesses a large number of advantages including low resistivity, high intrinsic spin Hall conductivity, and so on, has been extensively studied as the most likely candidate for SOT applications. [ 17,18 ] Meanwhile, the reported values of for pure Pt were generally low, for example, ≈0.06–0.16 (20‐44 ).…”