Deterministic Switching of Perpendicular Ferromagnets by Higher harmonics of Spin-orbit Torque in Noncentrosymmetric Weyl Semimetals

Abstract

Field-free deterministic switching of perpendicular ferromagnets is a central challenge for spintronics applications, typically requiring explicit symmetry breaking. Here we show that deterministic switching can instead be achieved through higher angular harmonics of spin-orbit torques, even in systems that preserve in-plane mirror symmetries. Using a vector spherical harmonics expansion, we demonstrate that these higher-harmonic torque components naturally give rise to additional out-of-equator fixed points, enabling reliable magnetization reversal when their magnitude is comparable to conventional lowest-order torques. We illustrate this mechanism with first-principles calculations on the noncentrosymmetric Weyl ferromagnet PrAlGe, where the combination of Weyl-node band topology and strong spin-orbit coupling produces sizable higher-harmonic torque components. Because the Fermi surface is small, the conventional lowest-order torques are relatively weak, allowing the higher-order harmonics to compete on equal footing and strongly reshape the magnetization dynamics. The resulting spin dynamics confirm deterministic switching without additional symmetry breaking. Our results establish higher-harmonic spin-orbit torque as a key ingredient for understanding and controlling magnetization dynamics in topological and spintronic materials.

References in corpus (27)

• Weyl and Dirac Semimetals in Three Dimensional Solids
• Spin torque switching with the giant spin Hall effect of tantalum
• WannierTools: An open-source software package for novel topological materials
• Magnetic switching by spin torque from the spin Hall effect
• Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems
• Symmetry and magnitude of spin-orbit torques in ferromagnetic heterostructures
• Control of spin-orbit torques through crystal symmetry in WTe2/ferromagnet bilayers
• Roadmap of spin-orbit torques
• Spin-orbit torques in Co/Pt(111) and Mn/W(001) magnetic bilayers from first principles
• Theoretical prediction of magnetic and noncentrosymmetric Weyl fermion semimetal states in the R-Al-X family of compounds (R=rare earth, Al=aluminium, X=Si, Ge)
• Theory of Current-Induced Angular Momentum Transfer Dynamics in Spin-Orbit Coupled Systems
• Current Control of Magnetism in Two-Dimensional Fe3GeTe2
• Magnetism and anomalous transport in the Weyl semimetal PrAlGe: Possible route to axial gauge fields
• Observation of Weyl fermions in a magnetic non-centrosymmetric crystal
• Deterministic and non-volatile switching of all-van der Waals spin-orbit torque system above room temperature without external magnetic fields
• Quantum materials for energy-efficient neuromorphic computing
• Accessing new magnetic regimes by tuning the ligand spin-orbit coupling in van der Waals magnets
• WannSymm: A symmetry analysis code for Wannier orbitals
• First-principles calculation of spin-orbit torque in a Co/Pt bilayer
• First Principles Study of Angular Dependence of Spin-Orbit Torque in Pt/Co and Pd/Co Bilayers
• Bulk single crystal growth of the theoretically predicted magnetic Weyl semimetals $R$AlGe ($R$ = Pr, Ce)
• Unconventional spin-orbit torque in transition metal dichalcogenide/ferromagnet bilayers from first-principles calculations
• Interfacial contributions to spin-orbit torque and magnetoresistance in ferromagnet/heavy-metal bilayers
• Microscopic Origin of Spin-Orbit Torque in Ferromagnetic Heterostructures: A First Principles Approach
• Intrinsic staggered spin-orbit torque for the electrical control of antiferromagnets -- application to CrI${}_3$
• Anatomy of anomalous Hall effect due to magnetic fluctuations
• Angular dependence of spin-orbit torque in monolayer $F{e}_{3}GeT{e}_2$