Field-free spin–orbit torque switching in L1-FePt single layer with tilted anisotropy

Abstract

For real-world applications, it is desirable to realize field-free spin–orbit torque (SOT) switching in thin films with high perpendicular magnetic anisotropy (PMA). In this paper, we report that field-free SOT switching in a L10-FePt single layer with a large switching ratio of 26% is obtained by using a MgO ⟨100⟩⋀8°/⟨100⟩ miscut substrate. It is found that field-free switching depends on the direction of the imposed pulse current. Only when the electric current is along the y (010)-direction but not along the x (100)-direction does field-free switching happen, which can be attributed to the tilted PMA induced symmetry breaking in the x–z plane. Furthermore, under the field-free condition, our FePt single layer system exhibits stable multi-state magnetic switching behavior and nonlinear synaptic characteristics. This work paves the way to realize field-free SOT switching in the L10-FePt single layer, which will have significant impact on spin memory devices and synaptic electronics.

Field-Free Spin–Orbit Torque-Induced Magnetization Switching in the IrMn/CoTb Bilayers with a Spontaneous In-Plane Exchange Bias

“…First, the variation range of R H increases obviously with increasing I p . Then, these results unambiguously demonstrate that consecutive positive (negative) pulses result in a gradual increase (decrease) in R H , which corresponds to the potentiation (depression) of a synapse . Moreover, the variation range of R H with different current amplitudes can be used to mimic the synaptic behavior in which a stronger stimulus causes a larger change of synaptic weight.…”

“…Finally, the application of the multistate field-free magnetization switching has been investigated in our Hall-bar devices. In a biological nervous system, neuromorphic networks consist of two basic units: the neuron and synapse, and the synapse connects two neurons and modifies the connection strength through its weight . In a Hall-bar device, the Hall resistance is able to be tuned by the current density, which corresponds to the weight update of a synapse.…”

Spintronic Heterostructures for Artificial Intelligence: A Materials Perspective

“…Meanwhile, Tao et al also reported the field‐free magnetization switching in the L 1 0 ‐FePt system at a similar current density of ≈3 × 10 11 A m −2 . [ 182 ] Dong et al reported the magnetization switching in the same material at a slightly reduced current density of ≈1.3–1.4 × 10 11 A m −2 . [ 183 ] However, an additional symmetry‐breaking field of 1000 Oe was required in this study.…”

Spin–Orbit Torque-Driven Memristor in L10 FePt Systems with Nanoscale-Thick Layers for Neuromorphic Computing

“…Recently, the bulk SOT within a single ferrimagnetic layer has been extensively investigated, and there is no limitation on the thickness of the ferromagnetic layer. − Therefore, it is desirable to explore the memristors in nanomaterials with bulk SOT effect. Recently, intermediate magnetic states can be observed in L1 0 FePt with large bulk SOT efficiency, and field-free SOT switching can be achieved in L1 0 FePt systems. − The tunable nonvolatile values of resistance is the typical feature for memristors and, until now, there have been no reports on spin-torque memristors based on the L1 0 FePt systems.…”