Spin Pumping and Inverse Spin Hall Effect in Iridium Oxide

Abstract

Large spin‐to‐charge conversion (spin Hall angle) and spin Hall conductivity are prerequisites for development of next generation power efficient spintronic devices. In this context, heavy metals (e.g., Pt, W, etc.), topological insulators, and antiferromagnets are usually considered because they exhibit high spin–orbit coupling (SOC). In addition to the above materials, 5d transition metal oxide, for example, iridium oxide (IrO2) is a potential candidate which exhibits high SOC strength. Here a study of spin pumping and inverse spin Hall effect (ISHE), via ferromagnetic resonance (FMR), in IrO2/CoFeB system is reported. By investigating the in‐plane angular dependence of the ISHE voltage, the individual contribution of spin pumping and other spin rectification effects in the magnetic layer is identified. The authors' analysis shows significant contribution of spin pumping effect to the ISHE signal. It is shown that polycrystalline IrO2 thin film exhibits high spin Hall conductivity and spin Hall angle which are comparable to the values of Pt.

Spin-to-Charge Conversion in All-Oxide La2/3Sr1/3MnO3/SrIrO3 Heterostructures

“…On the other hand, SRE appear due to the synchronous nonlinear coupling between eddy currents (induced by the rf magnetic field coming from the CPW) and the time-varying magnetization of the FM film in the form of magnetoresistance and result in a contribution to the measured voltage signal, with both symmetric and antisymmetric components, that is difficult to suppress., ,,− However, SRE effects are expected to be negligible in our case due to the high resistivity of LSMO film compared to that of metallic FM’s (e.g., Py) where SRE are of the same order of magnitude of ISHE . Thus, the expected ISHE-induced transverse voltage signals should be fully symmetric and their amplitude V ISHE related to the properties of the material by the following expression: , V ISHE = italicwR θ SH λ sd 0.25em tanh ( t SIO 2 λ sd ) j normals where w is the width of the CPW signal line, R is the sheet resistance of the bilayer, t SIO is the thickness of the SIO thin film, θ SH is the spin Hall angle of the SIO, and λ sd is its spin diffusion length. The injected spin current j s can be expressed as , j normals = ( e G eff ↓ ↑ 4 π ) true( μ 0 h rf γ α LSMO / SIO true) 2 μ 0 M normals γ …”

“…On the other hand, SRE appear due to the synchronous nonlinear coupling between eddy currents (induced by the rf magnetic field coming from the CPW) and the time-varying magnetization of the FM film in the form of magnetoresistance and result in a contribution to the measured voltage signal, with both symmetric and antisymmetric components, that is difficult to suppress., 28,29,44−46 However, SRE effects are expected to be negligible in our case due to the high resistivity of LSMO film compared to that of metallic FM's (e.g., Py) where SRE are of the same order of magnitude of ISHE. 28 Thus, the expected ISHE-induced transverse voltage signals should be fully symmetric and their amplitude V ISHE related to the properties of the material by the following expression: 47,48 V wR t j tanh 2…”

Spin homojunction with high interfacial transparency for efficient spin-charge conversion

“…4E, we compare T and  DL j of our FM-FeRh/ AFM-FeRh homojunction with that of available and representative two-layer heterojunctions for spin-charge conversion, including heavy metals and alloys, transition-metal oxides, antiferromagnets, etc. (2,4,5,22,24,26,(45)(46)(47)(48)(49)(50)(51)(52). As a result, our FM-FeRh/AFM-FeRh spin homojunction has a high interfacial transparency T and a high  DL j , demonstrating its unique advantage for spin-charge conversion.…”

Spin dynamics and inverse spin Hall effect study in the metallic Pt/NiMn/CoFeB system

“…The details of the set-up can also be found elsewhere. 10,[13][14][15][16][17][18][19][20] 3 Results and discussion Resonance field (H res ) and linewidth (DH) are evaluated from the ferromagnetic resonance spectra. The FMR data (see Fig.…”