S. Majid. Mohseni | Searcharxiv

arXiv2020

Coexistence of exchange bias training effect and spin-orbit torque in IrMn-layer/ferromagnetic-ribbon heterostructures via magnetoimpedance effect

We investigate a possible correlation between spin orbit torque (SOT) and exchange-bias (EB) in IrMn-layer/ferromagnetic-ribbon heterostructure by performing magnetoimpedance (MI) measurements. To uncover this correlation, we benefit from EB training effect probed by MI effect at room temperature. A damping-like SOT driven by ac current through the antiferromagnetic IrMn applies to the ferromagnetic ribbon layer, determined by MI magnetic field and frequency sweeps. Importantly, magnitude of the SOT is observed to remain intact against EB training and decrease of EB through alternative magnetic field sweep cycles. Our results pave the way to better elucidate the EB effect, EB training and the SOT, useful for future spintronic elements.

cond-mat.mes-hall↗

arXiv2017

Spin-orbit-torque driven magnetoimpedance in Pt-layer/magnetic-ribbon heterostructures

When a flow of electron passes through a paramagnetic layer with strong spin-orbit-coupling such as platinum (Pt), a net spin current is produced via spin Hall effect (SHE). This spin current can exert a torque on the magnetization of an adjacent ferromagnetic layer which can be probed via magnetization dynamic response, e.g. spin-torque ferromagnetic resonance (ST-FMR). Nevertheless, that effect in lower frequency magnetization dynamic regime (MHz) where skin effect occurs in high permeability ferromagnetic conductors namely the magneto-impedance (MI) effect can be fundamentally important which has not been studied so far. Here, by utilizing the MI effect in magnetic-ribbon/Pt heterostructure with high magnetic permeability that allows the ac current effectively confined at the skin depth of ~100 nm thickness, the effect of spin-orbit-torque (SOT) induced by the SHE probed via MI measurement is investigated. We observed a systematic MI frequency shift that increases by increasing the applied current amplitude and thickness of the Pt layer (varying from 0 nm to 20 nm). In addition, the role of Pt layer in ribbon/Pt heterostructure is evaluated with ferromagnetic resonance (FMR) effect representing standard Gilbert damping increase as the result of presence of the SHE. Our results unveil the role of SOT in dynamic control of the transverse magnetic permeability probed with impedance spectroscopy as useful and valuable technique for detection of future SHE devices.

cond-mat.mes-hall↗