Article
Quantum Science & Technology
Biswajit Sahoo, Koustuv Roy, Pushpendra Gupta, Abhisek Mishra, Biswarup Satpati, Braj Bhusan Singh, Subhankar Bedanta
Summary: The study focuses on spin pumping and inverse spin Hall effect in an IrO2/CoFeB system. By analyzing the angular dependence of ISHE voltage, it identifies the significant contribution of spin pumping to the ISHE signal. The research shows that polycrystalline IrO2 thin film exhibits high spin Hall conductivity and spin Hall angle comparable to Pt.
ADVANCED QUANTUM TECHNOLOGIES
(2021)
Article
Physics, Applied
Qi Liu, Y. Zhang, L. Sun, Bingfeng Miao, X. R. Wang, H. F. Ding
Summary: In this study, we introduce a method to quantitatively determine the spin pumping-induced inverse spin Hall effect (SP-ISHE) voltage using the ST-FMR signal in the Py(Ni80Fe20)/Pt bilayer. The SP-ISHE voltage is found to have an opposite sign to the symmetric component of the ST-FMR voltage. After correction, the efficiency of both damping-like and field-like torques in the Py/Pt bilayer is further estimated based on Py thickness-dependent measurements.
APPLIED PHYSICS LETTERS
(2021)
Article
Multidisciplinary Sciences
Hongjun Xu, Ke Jia, Yuan Huang, Fanqi Meng, Qinghua Zhang, Yu Zhang, Chen Cheng, Guibin Lan, Jing Dong, Jinwu Wei, Jiafeng Feng, Congli He, Zhe Yuan, Mingliang Zhu, Wenqing He, Caihua Wan, Hongxiang Wei, Shouguo Wang, Qiming Shao, Lin Gu, Michael Coey, Youguo Shi, Guangyu Zhang, Xiufeng Han, Guoqiang Yu
Summary: Spin pumping from Cr2Ge2Te6 into Pt or W and detection of the spin current by inverse spin Hall effect are demonstrated. The magnetization dynamics and magnetic damping constant of the hybrid Cr2Ge2Te6/Pt system are measured. A high interface spin transmission efficiency is directly extracted, suggesting promising applications for integrating Cr2Ge2Te6 into low-temperature two-dimensional spintronic devices as the source of coherent spin or magnon current.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Amit Rothschild, Nadav Am-Shalom, Nirel Bernstein, Ma'yan Meron, Tal David, Benjamin Assouline, Elichai Frohlich, Jiewen Xiao, Binghai Yan, Amir Capua
Summary: The Ferris FMR is a wideband and highly sensitive ferromagnetic resonance method that measures the absorption line rather than its derivative, with at least an order of magnitude higher sensitivity compared to conventional FMR systems. Using this method, spin currents generated from the orbital Hall effect in pure Cu and Al are reported. Cu exhibits a large effective spin Hall angle exceeding that of Pt, while Al possesses an orbital Hall effect of opposite polarity as predicted by theory.
Article
Physics, Applied
Koustuv Roy, Abhisek Mishra, Pushpendra Gupta, Shaktiranjan Mohanty, Braj Bhusan Singh, Subhankar Bedanta
Summary: The study reveals the potential of antiferromagnetic materials as replacements for heavy metals in spintronic devices, the mechanism of spin pumping in CoFeB/IrMn heterostructures is driven by IrMn underneath, and the dominance of spin pumping in all samples is confirmed by angle dependent ISHE measurements.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Motomi Aoki, Ei Shigematsu, Ryo Ohshima, Teruya Shinjo, Masashi Shiraishi, Yuichiro Ando
Summary: In this study, it was found that the Low-frequency ST FMR signal enables high sensitivity detection of magnetization switching, while an additional background signal BG was observed, and the sign of the BG signal changes by changing the nonmagnetic material. Further investigation revealed that the BG signal is induced by spin-dependent unidirectional spin Hall magnetoresistance, which is not related to magnetization dynamics but has broader applicability.
Article
Materials Science, Multidisciplinary
Bibekananda Paikaray, Somesh Kumar Sahoo, Talluri Manoj, Kasilingam Sriram, Himalay Basumatary, Arabinda Haldar, Chandrasekhar Murapaka
Summary: The study reports a large spin mixing conductance in Ta/permalloy(Py) bilayer structures and reveals the dominance of spin pumping voltage component through in-plane angular-dependent ISHE voltage measurements. The increase in Py thickness enhances spin pumping and spin-dependent scattering, leading to increased voltage contributions from spin pumping and anisotropic magnetoresistance (AMR). The contribution of anomalous Hall effect (AHE) in Py is relatively small.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2022)
Article
Physics, Multidisciplinary
V. Fernandez Becerra, Mircea Trif, Timo Hyart
Summary: We study the properties of semiconducting nanowires with induced superconductivity and ferromagnetism, and find that spin pumping is quantized in the topologically nontrivial phase while charge pumping is not. In long topologically nontrivial nanowires, there is a one-to-one correspondence between quantized conductance, entropy change, and spin pumping. The observation of correlated and quantized peaks in conductance, entropy change, and spin pumping would provide strong evidence of Majorana zero modes.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Applied
Ranen Ben-Shalom, Nirel Bernstein, Stuart S. P. Parkin, See-Hun Yang, Amir Capua
Summary: This study compares the spin torque ferromagnetic resonance (STFMR) method with two other FMR-based methods for extracting the spin Hall angle theta(SH). Despite the complexity of the interactions involved, STFMR was found to be the most robust method, providing a more accurate determination of theta(SH).
APPLIED PHYSICS LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Xiaotian Cui, Shun Wang, Changwen Zhang, Qiang Cao, Qikun Huang
Summary: The study reports a spin Hall rectification effect (SHRE) in heavy-metal/ferromagnetic metal bilayers, which has fundamental physical properties and wide applications in microelectronic and spintronic devices. Experimental results show that the SHRE can couple with magnetic information and is non-volatile and controllable depending on the magnetization direction of the ferromagnetic layer, which opens up a new avenue for spintronics diode engineering based on SHRE.
Article
Materials Science, Multidisciplinary
Kang He, Jun Cheng, Man Yang, Yihui Zhang, Longqian Yu, Qi Liu, Liang Sun, Bingfeng Miao, Canming Hu, Haifeng Ding
Summary: Spin pumping is a widely used technique for generating pure spin current and studying spin-charge conversion. However, the rectified voltage from the planar Hall effect can complicate the analysis and lead to misleading results.
Article
Materials Science, Multidisciplinary
Kang He, Jun Cheng, Man Yang, Liang Sun, Wei Sun, Subhankar Bedanta, Antonio Azevedo, Bingfeng Miao, Haifeng Ding
Summary: This study presents a systematic investigation of spin rectification effect (SRE) in Co40Fe40B20 and Ni microstrips. The SREs from different physical mechanisms are quantitatively decomposed using a symmetry consideration and supported by angular-dependent analyses. The study provides a comprehensive understanding of SREs in ferromagnetic metal microstrips, which is beneficial for quantitative analyses in microwave-related studies in spintronics.
Article
Multidisciplinary Sciences
Sergi Martin-Rio, Carlos Frontera, Alberto Pomar, Lluis Balcells, Benjamin Martinez
Summary: In this study, a simple method is proposed to suppress the contribution of spin rectification effects to the inverse spin Hall effect by adjusting the sample width. Experimental results and numerical simulations confirm the effectiveness of this method.
SCIENTIFIC REPORTS
(2022)
Article
Materials Science, Multidisciplinary
Youbin Zheng, Dainan Zhang, Lichuan Jin, Yulong Liao, Yiheng Rao, Qinghui Yang, Xiangrong Wang, Huaiwu Zhang
Summary: A Ge1-x Bix alloy film was grown into a GeBi/yttrium iron garnet (YIG) spin heterojunction with a ferromagnetic insulator Y(3)Fe(5)O(12) garnet film wafer for the first time, and it was found that regulating the Bi ions content and enhancing the spin-orbit torque (SOT) can control the signal voltage amplitude, bandwidth, and waveform of the inverse spin Hall effect (ISHE). The Bi doping not only changes the electron concentration and mixing conductance of the GeBi/YIG bilayer but also increases the SOT between GeBi film and YIG film, thereby driving domain superfast reversal and enhancing the ISHE. Our research shows that the Ge1-x Bix/YIG (x = 11.6-22.7%) spin heterojunction is one of the best choices for future spin wave devices.
ACS MATERIALS LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Emanuele Longo, Lorenzo Locatelli, Matteo Belli, Mario Alia, Arun Kumar, Massimo Longo, Marco Fanciulli, Roberto Mantovan
Summary: Large-area antimony telluride (Sb2Te3) thin films were grown using metal organic chemical vapor deposition technique, and their interaction with Fe thin films resulted in an increase in the damping parameter, suggesting the occurrence of spin pumping. Introducing a 5 nm Au interlayer between Fe and Sb2Te3 led to the development of a spin pumping signal, indicating the absence of spin-to-charge conversion in Fe/Sb2Te3. This study sheds light on the correlation among the chemical-structural-magnetic properties of the Fe/Sb2Te3 interface.
ADVANCED MATERIALS INTERFACES
(2021)
Review
Physics, Condensed Matter
Takashi Kikkawa, Eiji Saitoh
Summary: The spin Seebeck effect (SSE) is a phenomenon where a spin current is generated in a magnetic material due to a temperature gradient, which can be detected electrically. Intensive studies have been conducted to understand the origin of SSE since its discovery in 2008. SSEs appear in various magnetic materials and reflect fundamental properties of magnets. This article reviews recent progress on SSE in different systems and emphasizes its emerging role as a probe of magnetic properties in solids. The recently discovered nuclear SSE is also briefly discussed.
ANNUAL REVIEW OF CONDENSED MATTER PHYSICS
(2023)
Article
Physics, Applied
Sadamichi Maekawa, Takashi Kikkawa, Hiroyuki Chudo, Jun'ichi Ieda, Eiji Saitoh
Summary: With the advancement of spin science and spintronics research, study on spin current has become increasingly important. Spin current has been used to explain new phenomena and electronic states and to organize conventional spintronics phenomena. In this article, recent developments in spin physics, spin current, and related phenomena are discussed, with a focus on the interaction between spin angular momentum and other forms of angular momentum. The article covers topics such as spin pumping, topological Hall torque, emergent inductor, spin Seebeck and Peltier effects, and the interaction between mechanical motion and electron/nuclear spins.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Hendrik Meer, Stephan Wust, Christin Schmitt, Paul Herrgen, Felix Fuhrmann, Steffen Hirtle, Beatrice Bednarz, Adithya Rajan, Rafael Ramos, Miguel Angel Nino, Michael Foerster, Florian Kronast, Armin Kleibert, Baerbel Rethfeld, Eiji Saitoh, Benjamin Stadtmueller, Martin Aeschlimann, Mathias Klaeui
Summary: The antiferromagnetic order in NiO/Pt thin film heterostructures can be altered by optical pulses. Using X-ray magnetic linear dichroism, the optically induced creation of antiferromagnetic domains can be visualized. The effect of different laser polarizations on domain formation can be studied to identify polarization-independent creation of 180 degrees domain walls and domains with different Neel vector orientations. By varying irradiation parameters, the switching mechanism was determined to be thermally induced. This study demonstrates the potential for optically creating antiferromagnetic domains, an important advancement in the functionalization of all optical switching mechanisms in antiferromagnets.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Physics, Applied
Miku Yoshida, Md. Riad Kasem, Aichi Yamashita, Ken-ichi Uchida, Yoshikazu Mizuguchi
Summary: Recently, researchers have been studying thermal switching as an important component for thermal management in electronic devices. In this study, a significant magneto-thermal-switching ratio (MTSR) was observed in pure Nb at temperatures below its superconducting transition temperature. The MTSR increased as the temperature decreased, reaching 650% at a temperature of 2.5 K and a magnetic field of 4.0 kOe. The thermal switching in superconductors with a large MTSR could greatly enhance the performance of low-temperature electronic devices.
APPLIED PHYSICS EXPRESS
(2023)
Article
Physics, Applied
Atsushi Takahagi, Ryo Iguchi, Hosei Nagano, Ken-ichi Uchida
Summary: We find that the temperature measurement sensitivity in LITR can be improved by incorporating a thermochromic liquid crystal (TLC) into a transducer. The estimated thermoreflectance coefficient of a TLC/Pt hybrid film reaches >2 x 10(-2) K-1 at low excitation frequencies, which is two orders of magnitude greater than typical metallic films. Using the TLC/Pt film, we were able to detect temperature changes with a resolution of about 10 μK due to Joule heating and the spin Peltier effect, surpassing the resolution achieved with an Au film despite the lower reflected light intensity of the TLC/Pt film.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Ryo Iguchi, Daisuke Fukuda, Jun Kano, Takashi Teranishi, Ken-ichi Uchida
Summary: We present a direct measurement method for electrocaloric effects in dielectric materials based on lock-in thermography technique. The method utilizes sinusoidal excitation and multi-harmonic detection to measure the actual temperature change in the frequency domain, even when the electrocaloric effect exhibits a nonlinear response. We demonstrated the method by measuring the temperature dependence of electric-field-induced temperature change in Sr-doped BaTiO3 systems and extracting the pure electrocaloric contribution free from heat losses and Joule heating.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Takahiro Chiba, Ryo Iguchi, Takashi Komine, Yasuhiro Hasegawa, Ken-ichi Uchida
Summary: The Thomson effect can induce heat release or absorption in conductors when a charge current and a temperature gradient are simultaneously applied. In this study, we investigate the temperature distribution due to the Thomson-effect-induced heat release/absorption in junctionless single conductors, which can act as a temperature modulator. We also analyze the temperature distribution in realistic conductors. Our findings show that for conductors with a large Thomson coefficient, the temperature derivative of the Seebeck coefficient and the Thomson-effect-induced heat absorption can overcome Joule heating, resulting in current-induced cooling in the bulk region. We also demonstrate the feedback effect of the Thomson effect, which stabilizes the system temperature to one side of the heat bath, indicating the dependence of the Thomson effect on position and local temperature gradient. This work lays the foundation for thermal management utilizing the Thomson effect.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Zhenyu Zhou, William Frost, David C. Lloyd, Takeshi Seki, Takahide Kubota, Rafael Ramos, Eiji Saitoh, Koki Takanashi, Atsufumi Hirohata
Summary: Recent development in neuromorphic computation allows for low power, highly efficient calculations surpassing conventional von Neumann computation. Realistic synaptic operation requires potentiation through reducing electrical resistance of artificial synapses. A recent study demonstrated current-induced crystallisation in a magnetoresistive junction with a ferromagnetic Heusler alloy, which can be extended to epitaxially-grown Heusler alloys for realistic synaptic computation.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Instruments & Instrumentation
Maki Umeda, Hiroyuki Chudo, Masaki Imai, Nana Sato, Eiji Saitoh
Summary: We have developed experimental equipment to observe the Barnett effect at low temperatures. By rotating the sample bidirectionally using a temperature-controlled high-pressure gas, we detected the stray field generated by the Barnett effect using a fluxgate magnetic sensor. The magnetic susceptibility of the sample was estimated to be of the same order of magnitude as that due to the Barnett effect, by replacing the rotor with a solenoid coil. Measurements on commercial magnetite nanogranules confirmed the accordance of the g' factor between the experimental results using the present setup and those of our previous study performed at room temperature.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2023)
Article
Materials Science, Multidisciplinary
K. K. Meng, J. K. Chen, Y. Wu, X. G. Xu, T. Kikkawa, L. P. Sun, D. Z. Hou, Q. Li, N. N. Zhang, Z. G. Fu, T. Zhu, Y. Jiang, E. Saitoh
Summary: In this study, the quantum correction to the anomalous Hall effects (AHEs) in magnetic PtMnGe (PMG) thin films was investigated. It was found that the quantum correction to the transport behavior in the two-dimensional PMG system remains robust, even in the presence of spin-dependent scattering.
Article
Chemistry, Physical
Chanho Park, Jae Won Choi, No-Won Park, Gil-Sung Kim, Takashi Kikkawa, Eiji Saitoh, Sang-Kwon Lee
Summary: Recently, efforts have been made to improve the spin-voltage in Pt/Y3Fe5O12 (Pt/YIG) structures by inserting thin ferromagnetic interlayers, such as monolayer transition metal dichalcogenide (TMDC) layers. However, the role of monolayer TMDC interlayers in Pt/YIG systems and their temperature dependence remain unexplored. In this study, we investigated the temperature-dependent longitudinal spin Seebeck effect (LSSE) in Pt/YIG bilayer and Pt/ML MoS2/YIG trilayer systems. Our findings indicate that the inverse spin Hall effect (ISHE) voltages of Pt/ML MoS2/YIG are significantly lower compared to Pt/YIG system, due to the magnetic selection rule and diamagnetic ML MoS2 interlayer hindering the movement of spins generated at the interface in Pt/YIG structure.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Materials Science, Multidisciplinary
Hiroto Adachi, Naoshi Ikeda, Eiji Saitoh
Summary: In comparison to transport of spin polarization in ferromagnets, transport of electric polarization in ferroelectrics remains less explored. Taking an excitonic insulator model of electronic ferroelectricity as a prototypical example, we theoretically investigate the low-energy dynamics and transport of electric polarization by microscopically constructing the Ginzburg-Landau action. We show that, because of the scalar nature of the excitonic order parameter, only the longitudinal fluctuations are relevant to the transport of electric polarization. We also formulate the electric-polarization diffusion equation, in which the electric-polarization current is defined purely electronically without recourse to the lattice degrees of freedom.
Article
Materials Science, Multidisciplinary
C. Schmitt, L. Sanchez-Tejerina, M. Filianina, F. Fuhrmann, H. Meer, R. Ramos, F. Maccherozzi, D. Backes, E. Saitoh, G. Finocchio, L. Baldrati, M. Klaeui
Summary: In this study, we demonstrate that arbitrary-shaped T domains can be generated in antiferromagnetic NiO/Pt bilayers through switching driven by electrical current pulses. The domain walls between the T domains have spins pointing towards the average direction of the two T domains, indicating the absence of strong Lifshitz invariants. The micromagnetic modeling suggests that the domain wall is formed by strain distributions in the NiO thin film induced by the MgO substrate.
Article
Materials Science, Multidisciplinary
Hiroki Arisawa, Shunsuke Daimon, Yasuyuki Oikawa, Takashi Kikkawa, Eiji Saitoh
Summary: The spatial dependence of magnetization dynamics in a Y3Fe5O12 film under a magnetic-field gradient is investigated using local spin pumping and inverse spin-Hall effects. The results show that when microwaves are irradiated locally, magnetization precession is excited at a distant position from the irradiation location. By analyzing the field and microwave frequency dependence, it is found that the observed magnetization dynamics are due to nonlocal resonance of magnetization and spatial changes in spin-wave dispersion under the magnetic-field gradient, suggesting the potential to realize a microwave spectrometer known as a spin-wave cochlea.
Article
Materials Science, Multidisciplinary
Koichi Oyanagi, Saburo Takahashi, Takashi Kikkawa, Eiji Saitoh
Summary: We have theoretically studied the spin Seebeck effect (SSE) in a bilayer system of normal metal (NM) and paramagnetic insulator (PI). By considering the spin-flip scattering through interfacial exchange coupling, we calculated the thermal spin pumping from PI to NM and backflow spin current from NM to PI using a linear response approach. Our results show the appearance of a finite spin current at the interface under a temperature difference between spins in NM and PI, which increases with the density of localized spin S. Additionally, our model successfully explains the experimentally observed reduction of paramagnetic SSE in Pt/Gd3Ga5O12 when the Zeeman energy is comparable to the thermal energy.
