This paper studies spin–orbit torque (SOT) switching behaviors in synthetic antiferromagnet (SyAF) structures of Ta/[Pt/Co]m/Ru/[Co/Pt]n, which are asymmetric between the upper multilayer (UML) and the bottom multilayer (BML). The SOT-induced magnetization switching loops show multiple transitions of switching orientations between clockwise and anticlockwise with an increasing in-plane magnetic field, determined by the effects of the Dzyaloshinskii–Moriya interaction from both the BML and UML in the different stacking structures. Moreover, the field-free SOT switching was observed in the structure of Ta/[Pt/Co]3/Ru (0.5)/[Co/Pt]4. It can be attributed to the horizontal component of magnetic moments in its UML acting as an equivalent field. Therefore, the SyAF structures could be potential candidates for the future SOT-based spintronic devices.
A strain‐mediated perpendicular magnetic anisotropy (PMA) and current‐induced magnetization switching via spin–orbit torque (SOT) in PbMg1/3Nb2/3O3‐PbTiO3 (PMN‐PT)/Ta/Pt/Co/Pt ferromagnetic heterostructures are reported. It is found that the PMA changes regularly with the preloaded lateral electric field. The SOT‐based current‐induced magnetization switching also shows a reversible trend via applying a lateral electric field. Domain wall propagation driven by electric field is observed directly under a fixed perpendicular magnetic field by magnetic optical Kerr (MOKE) microscope. These behaviors can be attributed to the strain from the PMN‐PT substrates induced by the piezoelectric effect under electric field. Basing on the domain wall motion mechanism, repeatable resistance states of the Hall bar can be controlled by external electric field under a small auxiliary magnetic field, which enables the information recorded in the device can be programmed by voltage. This study provides a potential method to design the electric field controlled spintronic devices.
In this work, we have prepared an antiferromagnetic insulated α-Fe2O3 film with a large out-of-plane magnetic component and studied the spin Hall magnetoresistance (SMR) in α-Fe2O3/Pt bilayers. Both angular-dependent magnetoresistance and field-dependent magnetoresistance have featured a sign change characteristic with varying temperature, which is ascribed to the competition between a modulated interface magnetic state and an antiferromagnetic bulk state of the α-Fe2O3 film. According to a generalized theoretical model, which takes the effective spin conductance into consideration, the spin transport can be mathematically expressed as the change of field dependent average spin operators with varying temperature. The critical temperature also depends on the α-Fe2O3 film thickness and the magnetic field, which are ascribed to the magnons transport and long-range order of non-collinear spin textures, respectively. Furthermore, we have given a phenomenological form to fit the SMR curves in the critical temperature interval, which further reveals the origin of SMR with complex magnetic structures.
We report different types of perpendicular exchange bias (PEB) in the stacks of Ta/Pt/Co/IrMn/Pt. The PEB type can be modified through applying a perpendicular magnetic field during deposition or annealing. In addition, the spin-orbit torque (SOT) based current-induced magnetization switching is obviously affected by the PEB type. The magnetic anisotropy of the Co layer can be affected by the PEB type resulting in different magnetization switching behaviors. The Co layer with unidirectional anisotropy gives rise to different critical current densities for the SOT switching due to the pinning effect from the uncompensated spins of the antiferromagnetic IrMn layer. However, randomly aligned uncompensated spins result in symmetric SOT-based switching behaviors. The study demonstrates the controllable PEB and its effect on the SOT switching, which is helpful to the further understanding of the spin structure at the interface of a ferromagnet/antiferromagnet.
We report a strain-mediated
giant magnetoresistance (GMR) in spin valves (SPVs) grown on shape
memory alloys (SMAs). The SPVs with a stacking structure of Al2O3/Co90Fe10/Cu/Co90Fe10/IrMn/Pt were deposited on NiTi and NiTiNb SMA substrates
with and without predeformation. The GMR of the SPVs on the precompressed
NiTi substrates changes after annealing, whereas the one on SMAs without
predeformation remains unchanged under the same annealing treatment.
Especially, the GMR of the SPVs on the NiTiNb substrates can be reversibly
modulated under a thermocycling treatment on account of the shape
memory effect caused by the phase transitions of NiTiNb. The study
demonstrates a new strain-mediated approach to reversibly control
GMR through phase transitions, which provides a potential way to design
strain-sensitive spintronic devices.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.