Large inverse spin Hall effect in the antiferromagnetic metal Ir20Mn80 (original) (raw)
Related papers
Spin pumping and inverse spin Hall effect in CoFeB/IrMn heterostructures
2021
High spin to charge conversion efficiency is a requirement for spintronic devices, which are governed by spin pumping and the inverse spin Hall effect (ISHE). In the last decade, ISHE and spin pumping have been heavily investigated in ferromagnet/heavy metal (HM) heterostructures. Recently, antiferromagnetic (AFM) materials have been found to be a good replacement for HMs because AFMs exhibit terahertz spin dynamics, high spin–orbit coupling, and absence of the stray field. In this context, we have performed the ISHE in CoFeB/IrMn heterostructures. Spin pumping studies are carried out for Co40Fe40B20(12 nm)/Cu(3 nm)/Ir50Mn50(t nm)/AlO x (3 nm) samples where t value varies from 0 to 10 nm. Damping in all the samples is higher than in the single layer CoFeB which indicates that spin pumping due to IrMn is the underneath mechanism. Further, the spin pumping in the samples is confirmed by angle dependent ISHE measurements. We have also disentangled other spin rectifications effects and ...
Physical Review B, 2018
We report experiments demonstrating the spin to charge current conversion by means of the inverse spin Hall effect in ultrathin films of the metallic antiferromagnet Mn 2 Au at room temperature. The Mn 2 Au films, of different thicknesses, were grown by dc sputtering directly onto crystalline films of the ferrimagnetic insulator yttrium iron garnet (YIG). The spin currents are generated in the YIG film by two different processes, spin pumping effect (SPE) and spin Seebeck effect (SSE). In the SPE experiments we use microwave-driven ferromagnetic resonance of the YIG film to generate a spin current that is injected into the Mn 2 Au, while in the SSE experiments the spin current is generated by a thermal gradient across the YIG film in the configuration of the longitudinal spin Seebeck effect. From these measurements, we obtain for Mn 2 Au at room temperature a spin-diffusion length, λ S , of 1.6 nm and a spin Hall angle, θ SH ≈ 0.04, which is comparable to the value for platinum.
Unidirectional Spin Hall Magnetoresistance in Antiferromagnetic Heterostructures
Physical Review Letters, 2023
Unidirectional spin Hall magnetoresistance (USMR) has been widely reported in the heavy metal / ferromagnet (HM/FM) bilayer systems. We observe the USMR in the Pt/α-Fe2O3 bilayers where the α-Fe2O3 is an antiferromagnetic (AFM) insulator. Systematic field and temperature dependent measurements confirm the magnonic origin of the USMR. The appearance of AFM-USMR is driven by the imbalance of creation and annihilation of AFM magnons by spin orbit torque due to thermal random field. However, unlike its ferromagnetic counterpart, theoretical modeling reveals that the USMR in Pt/α-Fe2O3 is determined by the antiferromagtic magnon number, and with a non-monotonic field dependence. Our findings extend the generality of the USMR which pave the ways for the highly sensitive detection of AF spin state.
Spin colossal magnetoresistance in an antiferromagnetic insulator
Nature materials, 2018
Colossal magnetoresistance (CMR) refers to a large change in electrical conductivity induced by a magnetic field in the vicinity of a metal-insulator transition and has inspired extensive studies for decades. Here we demonstrate an analogous spin effect near the Néel temperature, T = 296 K, of the antiferromagnetic insulator CrO. Using a yttrium iron garnet YIG/CrO/Pt trilayer, we injected a spin current from the YIG into the CrO layer and collected, via the inverse spin Hall effect, the spin signal transmitted into the heavy metal Pt. We observed a two orders of magnitude difference in the transmitted spin current within 14 K of the Néel temperature. This transition between spin conducting and non-conducting states was also modulated by a magnetic field in isothermal conditions. This effect, which we term spin colossal magnetoresistance (SCMR), has the potential to simplify the design of fundamental spintronics components, for instance, by enabling the realization of spin-current s...
Science advances, 2016
There has been considerable interest in spin-orbit torques for the purpose of manipulating the magnetization of ferromagnetic elements for spintronic technologies. Spin-orbit torques are derived from spin currents created from charge currents in materials with significant spin-orbit coupling that propagate into an adjacent ferromagnetic material. A key challenge is to identify materials that exhibit large spin Hall angles, that is, efficient charge-to-spin current conversion. Using spin torque ferromagnetic resonance, we report the observation of a giant spin Hall angle [Formula: see text] of up to ~0.35 in (001)-oriented single-crystalline antiferromagnetic IrMn3 thin films, coupled to ferromagnetic permalloy layers, and a [Formula: see text] that is about three times smaller in (111)-oriented films. For (001)-oriented samples, we show that the magnitude of [Formula: see text] can be significantly changed by manipulating the populations of various antiferromagnetic domains through ...
Journal of Physics D: Applied Physics, 2014
We carried out a concerted effort to determine the absolute sign of the inverse spin Hall effect voltage generated by spin currents injected into a normal metal. We focus on yttrium iron garnet (YIG)|platinum bilayers at room temperature, generating spin currents by microwaves and temperature gradients. We find consistent results for different samples and measurement setups that agree with theory. We suggest a right-hand-rule to define a positive spin Hall angle corresponding to with the voltage expected for the simple case of scattering of free electrons from repulsive Coulomb charges.
Spin Hall magnetoresistance in antiferromagnet/heavy-metal heterostructures
2018
We investigate the spin Hall magnetoresistance in thin film bilayer heterostructures of the heavy metal Pt and the antiferromagnetic insulator NiO. While rotating an external magnetic field in the easy plane of NiO, we record the longitudinal and the transverse resistivity of the Pt layer and observe an amplitude modulation consistent with the spin Hall magnetoresistance. In comparison to Pt on collinear ferrimagnets, the modulation is phase shifted by 90 and its amplitude strongly increases with the magnitude of the magnetic field. We explain the observed magnetic field-dependence of the spin Hall magnetoresistance in a comprehensive model taking into account magnetic field induced modifications of the domain structure in antiferromagnets. With this generic model we are further able to estimate the strength of the magnetoelastic coupling in antiferromagnets. Our detailed study shows that the spin Hall magnetoresistance is a versatile tool to investigate the magnetic spin structure ...
Transformation of spin current by antiferromagnetic insulators
It is demonstrated theoretically that a thin layer of an anisotropic antiferromagnetic (AFM) insulator can effectively conduct spin current through the excitation of a pair of evanescent AFM spin wave modes. The spin current flowing through the AFM is not conserved due to the interaction between the excited AFM modes and the AFM lattice, and, depending on the excitation conditions, can be either attenuated or enhanced. When the phase difference between the excited evanescent modes is close to π/2, there is an optimum AFM thickness for which the output spin current reaches a maximum, that can significantly exceed the magnitude of the input spin current. The spin current transfer through the AFM depends on the ambient temperature and increases substantially when temperature approaches the Neel temperature of the AFM layer. Progress in modern spintronics critically depends on finding novel media that can serve as effective conduits of spin angular momentum over large distances with minimum losses [1–3]. The mechanism of spin transfer is reasonably well-understood in ferromagnetic (FM) metals [4, 5] and insulators [3, 4, 6–9], but there are only very few theoretical papers describing spin current in an-tiferromagnets (AFM) (see, e.g., [10]). The recent experiments [11–13] have demonstrated that a thin layer of a dielectric AFM (NiO, CoO) could effectively conduct spin current. The transfer of spin current was studied in the FM/AFM/Pt trilayer structure (see Fig. 1). The FM layer driven in ferromagnetic resonance (FMR) excited spin current in a thin layer of AFM, which was detected in the adjacent Pt film using the inverse spin Hall effect (ISHE). It was also found in [13] that the spin current through the AFM depends on the ambient temperature and goes through a maximum near the Neel temperature T N. The most intriguing feature of the experiments was the fact that for a certain optimum thickness of the AFM layer (∼ 5 nm) the detected spin current had a maximum [11, 12], which could be even higher than in the absence of the AFM spacer [12]. The spin current transfer in the reversed geometry, when the spin current flows from the Pt layer driven by DC current through the AFM spacer into a microwave-driven FM material has been reported recently in [14]. The experiments [11–14] posed a fundamental question of the mechanism of the apparently rather effective spin current transfer through an AFM dielectric. A possible mechanism of the spin transfer through an easy-axis AFM has been recently proposed in [10]. However, this uniaxial model can not explain the non-monotonous dependence of the transmitted spin current on the AFM layer thickness and the apparent " amplification " of the spin current seen in the experiments [11, 12] performed with the bi-axial NiO AFM layer [15]. In this Letter, we propose a possible mechanism of spin current transfer through anisotropic AFM dielectrics, which may explain all the peculiarities of the experiments FIG. 1. Sketch of the model of spin current transfer through an AFM insulator based on the experiment [11]. The FM layer excites spin wave excitations in the AFM layer. The output spin current (at the AFM/Pt interface) is detected by the Pt layer through the inverse spin Hall effect (ISHE). [11, 12, 14]. Namely, we show that the spin current can be effectively carried by the driven evanescent spin wave excitations, having frequencies that are much lower than the frequency of the AFM resonance. We demonstrate that the angular momentum exchange between the spin subsystem and the AFM lattice plays a crucial role in this process, and may lead to the enhancement of the spin current inside the AFM layer. We consider a model of a simple AFM having two magnetic sublattices with the partial saturation magnetiza-tion M s. The distribution of the magnetizations of each sublattice can be described by the vectors M 1 and M 2 , |M 1 | = |M 1 | = M s. We use a conventional approach for describing the AFM dynamics by introducing the vectors of antiferromagnetism (l) and magnetism (m) [16–19]: l = (M 1 − M 2)/(2M s), m = (M 1 + M 2)/(2M s). (1) Assuming that all the magnetic fields are smaller then the exchange field H ex and neglecting the bias magnetic field, that is used to saturate the FM layer, the effective AFM Lagrangian can be written as [16, 18, 19]:
Spin Pumping and Inverse Spin Hall Effect in Iridium Oxide
arXiv: Materials Science, 2020
Large charge-to-spin 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, antiferromagnets are usually considered because they exhibit high spin-orbit coupling (SOC). In addition to the above materials, 5d transition metal oxide e.g. Iridium Oxide (IrO 2 ) is a potential candidate which exhibits high SOC strength. Here we report a study of spin pumping and inverse spin Hall effect (ISHE), via ferromagnetic resonance (FMR), in IrO 2 /CoFeB system. We identify the individual contribution of spin pumping and other spin rectification effects in the magnetic layer, by investigating the in-plane angular dependence of ISHE signal. Our analysis shows significant contribution of spin pumping effect to the ISHE signal. We show that polycrystalline IrO 2 thin film exhibits high spin Hall conductivity and spin Hall angle which are c...
Detection of Interfacial Spin Accumulation Induced by Anomalous Hall Effect in Ferromagnets
Journal of Magnetism and Magnetic Materials, 2019
We present an experimental observation of interfacial spin accumulation induced by anomalous Hall effect (AHE) in ferromagnets (FMs) in a multilayer structure of FM/YIG/Pt, where the direction of charge current injection in FM layer is perpendicular to the direction of voltage detection in Pt layer. In this structure, the magnon-mediated drag voltage (V drag) due to the interfacial spin accumulation induced by AHE, can be unambiguously separated from spin Seebeck voltage (V SSE) by sweeping or rotating the applied magnetic field. Field-dependent spin accumulation induced by AHE has been observed by comparison of nonlocal voltages between Ni/Cu/YIG/Pt and Pt/YIG/Pt samples. Furthermore, we demonstrate that the AHE voltage strongly depends on the spin polarization of conductivity and spin Hall angles of electrons with opposite spins in FMs. Our results show a prospect for FMs to be field-control spin generators via AHE, and provide a new viewpoint to realize the AHE.