ABSTRACT
Electrical control of magnetic properties is crucial for low-energy memory and logic spintronic devices. We find that the magnetic properties of ferrimagnetic CoGd can be altered through ionic liquid gating. Gate voltages manipulate the opposite magnetic moments in Co and Gd sublattices and induce a giant magnetic compensation temperature change of more than 200 K in Pt/CoGd/Pt heterostructures. The electrically controlled dominant magnetic sublattice allows voltage-induced magnetization switching. Both experiments and theoretical calculations demonstrate that the significant modulations of compensation temperature are relevant to the reduced Gd moments due to the presence of hydrogen ions at positive voltages as well as the enhanced Co moments and reduced Gd moments due to the injection of oxygen ions at negative voltages. These findings expand the possibilities for all-electric and reversible magnetization control in the field of spintronics.
ABSTRACT
The orbital Hall effect and the interfacial Rashba effect provide new approaches to generate orbital current and spin-orbit torque (SOT) efficiently without the use of heavy metals. However, achieving efficient dynamic control of orbital current and SOT in light metal oxides has proven challenging. In this study, it is demonstrated that a sizable magnetoresistance effect related to orbital current and SOT can be observed in Ni81 Fe19 /CuOx /TaN heterostructures with various CuOx oxidization concentrations. The ionic liquid gating induces the migration of oxygen ions, which modulates the oxygen concentration at the Ni81 Fe19 /CuOx interface, leading to reversible manipulation of the magnetoresistance effect and SOT. The existence of a thick TaN capping layer allows for sophisticated internal oxygen ion reconstruction in the CuOx layer, rather than conventional external ion exchange. These results provide a method for the reversible and dynamic manipulation of the orbital current and SOT generation efficiency, thereby advancing the development of spin-orbitronic devices through ionic engineering.
ABSTRACT
Generation and manipulation of spin current are the cores of spintronic devices, which are intensely pursued. Heavy metals with strong spin-orbit coupling are commonly used for the generation of spin current, but are incompatible with the mass production of devices, and the polarization of spin current is limited to be in-plane. Here, it is shown that the spin current with strong out-of-plane polarization component can be generated and transmitted in Ni81 Fe19 /Cu-CuOx bilayer with sideways and top oxidizations. The charge-to-spin current conversion efficiency can be enhanced through the spin currents consisting of both out-of-plane polarization (σz ) and in-plane polarization (σy ) induced by spin-vorticity coupling. Such a spin current is demonstrated to be closely related to the lateral oxidization gradient and can be controlled by changing the temperatures and times of annealing. The finding here provides a novel degree of freedom to produce and control the spin current in spintronic devices.
ABSTRACT
The manipulation of charge-to-spin current conversion and spin-orbit torque (SOT) is of great interest due to its profound physics and potential applications. Controlling the spin current through the electric field provides a perspective for highly efficient SOT devices. Here, we use H2O-doped ionic liquid gating to realize the reversible and nonvolatile manipulation of the spin Hall effect of Pt, and the spin Hall angle can be modulated by 48% within an accessible gate voltage range. The increase in the spin Hall angle is demonstrated to be caused by the adsorption of hydrogen ions on the Pt surface and the consequent enhancement of the spin Hall conductivity under positive voltage. Furthermore, the enhancement of the spin Hall angle is beneficial to reduce the critical current density for driving the domain wall motion. These results supply a method for the dynamic control of the charge-to-spin current conversion, which will promote the development of spintronic devices driven by electric fields.
