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Terahertz Emission From an Exchange-Coupled Synthetic Antiferromagnet
摘要： We report on terahertz emission from Fe-Mn-Pt/Ru/Fe-Mn-Pt and Pt/Co-Fe-B/Ru/Co-Fe-B/Pt synthetic antiferromagnet (SAF) structures upon irradiation by a femtosecond laser; the former is via the anomalous Hall effect, whereas the latter is through the inverse spin Hall effect. The antiparallel alignment of the two ferromagnetic layers leads to a terahertz emission peak amplitude that is almost double that of a corresponding single-layer or bilayer emitter with the same equivalent thickness. In addition, we demonstrate by both simulation and experiment that terahertz emission provides a powerful tool to probe the magnetization reversal processes of individual ferromagnetic layers in a SAF structure, as the terahertz signal is proportional to the vector difference (M1 ? M2) of the magnetizations of the two ferromagnetic layers.
关键词： anomalous Hall effect,synthetic antiferromagnet,terahertz emission,magnetization reversal,inverse spin Hall effect
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Self-Aligned, Selective Area Poly-Si/SiO <sub/>2</sub> Passivated Contacts for Enhanced Photocurrent in Front/Back Solar Cells
摘要： Spin circuits with four component voltages and currents have been developed and used in the past to analyze various structures, which include non-collinear ferromagnets. Recent demonstrations of large spin orbit torques in heavy metals like Pt, Ta, and W open up new possibilities in spintronic applications by providing an alternative way to write information into a magnet. Here, we extend the four component (one charge and three spins) conductance matrix to include materials with spin Hall effect based on the standard diffusion equation. Our proposed spin circuit successfully reproduces standard results like spin Hall effect (SHE), inverse spin Hall effect, and spin Hall magnetoresistance. This circuit representation also makes it straightforward to analyze new configurations. We present two examples, namely, 1) the possibility of spin injection using giant SHE (GSHE) materials into semiconductors without tunneling barriers, and 2) the effect of spin ground on one surface to enhance spin current injection from the opposite surface in a thin GSHE sample. Finally, we provide an elemental conductance matrix for a small cubic structure which can be used as a building block to analyze any arbitrarily shaped GSHE material.
关键词： four component spin circuit,spin Hall magnetoresistance,Giant spin Hall effect,conductance matrix,inverse spin Hall effect,spin ground/sink,spin Hall effect
更新于2025-09-23 15:19:57
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Spin pumping and laser modulated inverse spin Hall effect in yttrium iron garnet/germanium heterojunctions
摘要： In this work, undoped semiconductors, germanium (Ge) and germanium tin (GeSn), were grown on ferrimagnetic insulator yttrium iron garnet (YIG) thin ?lms using ultra-high vacuum molecular beam epitaxy. The crystallinity of the structure was determined from x-ray diffraction and high-resolution transmission electron microscopy combined with energy dispersive x-ray spectroscopy. Both spin pumping and inverse spin Hall effects (ISHEs) of YIG/Ge and YIG/GeSn heterojunctions have been investigated with the help of broadband ferromagnetic resonance (FMR). We observe that the spin mixing conductances of YIG/Ge (60 nm) and YIG/GeSn (60 nm) are 5.4 (cid:2) 1018 m(cid:3)2 and 7.2 (cid:2) 1018 m(cid:3)2, respectively, responsible for giant spin current injection. Furthermore, it is found that spin pumping injects giant spin current from ferrimagnetic YIG into the Ge semiconductor. The infrared laser modulated ISHE was examined using heavy metal platinum as a spin current collector. Also, it has been noted that the variation in the power of laser irradiation signi?cantly changed the ISHE voltage of YIG/Ge/Pt spin junctions, saturated magnetization, FMR linewidth, and Gilbert damping parameter of YIG, which could be attributed to the laser-induced thermal effect. The outcomes from this study are promising for the development of Ge-based spintronic and magnonic devices.
关键词： germanium tin,magnonics,germanium,spin pumping,inverse spin Hall effect,yttrium iron garnet,spintronics
更新于2025-09-23 15:19:57
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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - FBG Sensors Network Embedded in Spectrum-sliced WDM-PON Transmission System Operating on Single Shared Broadband Light Source
摘要： Spin circuits with four component voltages and currents have been developed and used in the past to analyze various structures, which include non-collinear ferromagnets. Recent demonstrations of large spin orbit torques in heavy metals like Pt, Ta, and W open up new possibilities in spintronic applications by providing an alternative way to write information into a magnet. Here, we extend the four component (one charge and three spins) conductance matrix to include materials with spin Hall effect based on the standard diffusion equation. Our proposed spin circuit successfully reproduces standard results like spin Hall effect (SHE), inverse spin Hall effect, and spin Hall magnetoresistance. This circuit representation also makes it straightforward to analyze new configurations. We present two examples, namely, 1) the possibility of spin injection using giant SHE (GSHE) materials into semiconductors without tunneling barriers, and 2) the effect of spin ground on one surface to enhance spin current injection from the opposite surface in a thin GSHE sample. Finally, we provide an elemental conductance matrix for a small cubic structure which can be used as a building block to analyze any arbitrarily shaped GSHE material.
关键词： spin ground/sink,spin Hall magnetoresistance,conductance matrix,Giant spin Hall effect,inverse spin Hall effect,four component spin circuit,spin Hall effect
更新于2025-09-19 17:13:59
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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Novel Approaches to Realize Plasmonic Intrinsic and Extrinsic Optical Fiber Sensors with High Sensitivity
摘要： Spin circuits with four component voltages and currents have been developed and used in the past to analyze various structures, which include non-collinear ferromagnets. Recent demonstrations of large spin orbit torques in heavy metals like Pt, Ta, and W open up new possibilities in spintronic applications by providing an alternative way to write information into a magnet. Here, we extend the four component (one charge and three spins) conductance matrix to include materials with spin Hall effect based on the standard diffusion equation. Our proposed spin circuit successfully reproduces standard results like spin Hall effect (SHE), inverse spin Hall effect, and spin Hall magnetoresistance. This circuit representation also makes it straightforward to analyze new configurations. We present two examples, namely, 1) the possibility of spin injection using giant SHE (GSHE) materials into semiconductors without tunneling barriers, and 2) the effect of spin ground on one surface to enhance spin current injection from the opposite surface in a thin GSHE sample. Finally, we provide an elemental conductance matrix for a small cubic structure which can be used as a building block to analyze any arbitrarily shaped GSHE material.
关键词： spin ground/sink,spin Hall magnetoresistance,conductance matrix,Giant spin Hall effect,inverse spin Hall effect,four component spin circuit,spin Hall effect
更新于2025-09-19 17:13:59
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Inverse Spin Hall Effect in Electron Beam Evaporated Topological Insulator Bi <sub/>2</sub> Se <sub/>3</sub> Thin Film
摘要： Spintronics exploiting pure spin current in ferromagnetic (FM)/heavy metals (HM) is a subject of intense research. Topological insulators having spin momentum locked surface states exhibit high spin–orbit coupling and thus possess a huge potential to replace the HM like Pt, Ta, W, etc. In this context, the spin pumping phenomenon in Bi2Se3/CoFeB bilayers has been investigated. Bi2Se3 thin films are fabricated by electron beam evaporation method on Si (100) substrate. In order to confirm the topological nature of Bi2Se3, low temperature magnetotransport measurement on a 30 nm thick Bi2Se3 film which shows 10% magnetoresistance (MR) at 1.5 K has been performed. A linear increase in MR with applied magnetic field indicates the presence of spin momentum-locked surface states. A voltage has been measured at room temperature to quantify the spin pumping which is generated via inverse spin Hall effect (ISHE). For the separation of spin rectification effects mainly produced by the FM CoFeB layer, in plane angular dependence of the dc voltage with respect to applied magnetic field has been measured. Our analysis reveals that spin pumping induced ISHE is the dominant contribution in the measured voltage.
关键词： spin pumping,inverse spin Hall effect,topological insulator/ferromagnetic interface,magnetoresistance,ferromagnetic resonance
更新于2025-09-10 09:29:36
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Evidence of Pure Spin-Current Generated by Spin Pumping in Interface Localized States in Hybrid Metal-Silicon-Metal Vertical Structures
摘要： Due to the difficulty to grow high quality semiconductors on ferromagnetic metals, the study of spin diffusion transport in Si was only limited to lateral geometry devices. In this work, by using ultra-high vacuum wafer-bonding technique, we have successfully fabricated metal-semiconductor-metal CoFeB/MgO/Si/Pt vertical structures. We hereby demonstrate pure spin-current injection and transport in the perpendicular current flow geometry over a distance larger than 2μm in n-type Si at room temperature. In those experiments, a pure propagating spin-current is generated via ferromagnetic resonance spin-pumping and converted into a measurable voltage by using the inverse spin-Hall effect occurring in the top Pt layer. A systematic study by varying both Si and MgO thicknesses reveals the important role played by the localized states at the MgO/Si interface for the spin-current generation. Proximity effects involving indirect exchange interactions between the ferromagnet and the MgO/Si interface states appears to be a prerequisite to establish the necessary out-of-equilibrium spin-population in Si under the spin-pumping action.
关键词： localized electronic states,wafer-bonding,inverse spin Hall effect,spin-current,spin pumping
更新于2025-09-09 09:28:46