Tuning spin-orbit torques across the phase transition in VO${}_2$/NiFe heterostructure

Abstract

The emergence of spin-orbit torques as a promising approach to energy-efficient magnetic switching has generated large interest in material systems with easily and fully tunable spin-orbit torques. Here, current-induced spin-orbit torques in VO${}_2$/NiFe heterostructures were investigated using spin-torque ferromagnetic resonance, where the VO${}_2$ layer undergoes a prominent insulator-metal transition. A roughly two-fold increase in the Gilbert damping parameter, $\alpha$, with temperature was attributed to the change in the VO${}_2$/NiFe interface spin absorption across the VO${}_2$ phase transition. More remarkably, a large modulation ($\pm$100%) and a sign change of the current-induced spin-orbit torque across the VO${}_2$ phase transition suggest two competing spin-orbit torque generating mechanisms. The bulk spin Hall effect in metallic VO${}_2$, corroborated by our first-principles calculation of spin Hall conductivity, ${\sigma }_{SH}\approx 10^4\frac{\hslash }{e}{\Omega }^{-1}{m}^{-1}$, is verified as the main source of the spin-orbit torque in the metallic phase. The self-induced/anomalous torque in NiFe, of the opposite sign and a similar magnitude to the bulk spin Hall effect in metallic VO${}_2$, could be the other competing mechanism that dominates as temperature decreases. For applications, the strong tunability of the torque strength and direction opens a new route to tailor spin-orbit torques of materials which undergo phase transitions for new device functionalities.

arXiv comment16 pages, 5 figures

References in corpus (22)

• Spin torque switching with the giant spin Hall effect of tantalum
• Spin Torque Ferromagnetic Resonance Induced by the Spin Hall Effect
• Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems
• Experimental observation of the spin-Hall effect in a two dimensional spin-orbit coupled semiconductor system
• Spin Transfer Torque Generated by the Topological Insulator Bi_2Se_3
• Electrical Detection of Spin Transport in Lateral Ferromagnet-Semiconductor Devices
• Highly efficient and tuneable spin-to-charge conversion through Rashba coupling at oxide interfaces
• Ultrafast magnetization switching by spin-orbit torques
• Room-temperature perpendicular magnetization switching through giant spin-orbit torque from sputtered BixSe(1-x) topological insulator material
• Spin-pumping into surface states of topological insulator α-Sn, spin to charge conversion at room temperature
• Orbital Torque: Torque Generation by Orbital Current Injection
• Comparison of spin-orbit torques and spin pumping across NiFe/Pt and NiFe/Cu/Pt interfaces
• Phase-Change Control of Interlayer Exchange Coupling
• Anomalous Spin-Orbit Torques in Magnetic Single-Layer Films
• Theory of Current-Induced Angular Momentum Transfer Dynamics in Spin-Orbit Coupled Systems
• Current-induced torques and interfacial spin-orbit coupling
• Intrinsic spin currents in ferromagnets
• Perspectives of Electrically generated spin currents in ferromagnetic materials
• Electric-field control of spin-orbit torques in perpendicularly magnetized W/CoFeB/MgO films
• Disentangling relativistic spin torques in a ferromagnet/semiconductor bilayer
• Optical control of magnetism in NiFe/VO2 heterostructures
• Large phase-transition-induced magnetic anisotropy change in (Co/Pt)2/VO2 heterostructure

Cited by in corpus (1)

• Tunable spin and orbital torques in Cu-based magnetic heterostructures