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

Abstract

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 transvers 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.

Controlling Magnetization of Gr/Ni Composite for Application in High-Performance Magnetic Sensors

“…It is noted in Figure 6c that for all investigated samples, with increasing frequency, the maximum MI ratio first increases, reaches a maximum at a particular frequency (10 MHz), and then decreases for higher frequencies. This trend can be interpreted by considering the relative contributions of DW motion and moment rotation to the transverse magnetic permeability and hence to the MI 20,23,51 . Note that as frequency increases well above 100 kHz, the contribution of DW motion is damped due to the presence of the eddy current and moment rotation becomes dominant 20 .…”

Exchange bias training effect in IrMn-layer/ferromagnetic-ribbon heterostructures probed with magnetoimpedance

“…In this work, we use magnetoimpedance (MI) effect as a probe of the EB and the TE in in FM/AFM heterostructures that is made of an amorphous FM Co68.15Fe4.35Si12.5B15 ribbon and a thin layer of polycrystalline Ir20Mn80 (IrMn). The MI effect is a classical electrodynamic phenomenon in conducting FM with high transverse magnetic permeability (𝜇 𝑡 ) as the electrical impedance changes against external dc magnetic field [28][29][30][31][32][33][34][35][36][37] . The MI is correlated with the skin depth (δ = (ρ/πμtf) 1/2 ), of the high frequency f current and 𝜇 𝑡 of the conducting FM with electric resistivity ρ.…”

“…From far viewpoints, as the FM ribbon is a thick structure with thickness of 20 µm, it is rather unexpected to observe the EB effect and hence the TE. However, the MI was shown in many literatures [29,30,32,34] to be a surface sensitive measurement technique with confined of the most ac current at 100 nm at the skin depth. Due to their high magnetic permeability, MI effect in such ribbons is very sensitive against tiny changes at the surface.…”

“…Due to their high magnetic permeability, MI effect in such ribbons is very sensitive against tiny changes at the surface. We showed that impedance spectroscopy can be used for detection of the spin-orbit torque resulting from the spin Hall effect in a Pt-layer/magnetic-ribbon heterostructures [30] . Moreover, older studies have shown asymmetric MI effect made by intense surface oxidation of such ribbons [38] .…”

Effect of YIG nanoparticle size and clustering in proximity-induced magnetism in graphene/YIG composite probed with magnetoimpedance sensors: Towards improved functionality, sensitivity and proximity detection

“…[27][28][29][30][31][32] They can tune the MI response mainly due to closure of magnetic flux path at the surface of the MI elements. Interestingly, MI sensing element preserves as a surface media to probe the spin-orbit torque due to non-magnetic Pt [33] and IrMn [34] layer, as the thin skin depth is quite sensitive against tiny changes at the surface.…”