Article
Chemistry, Physical
Longlong Zhang, Jun Zan, Yujuan Huang, Huiqin Cui, Yuying Hao
Summary: A mechanism for generating pure spin current in heterojunction organic solar cells is proposed, utilizing degenerate ground-state polymers for donor and acceptor to form solitons and separate spins without charge separations. This mechanism opens up a new avenue for potential organic spintronic devices.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Physical
Guocui Pan, Zhiqiang Yang, Haichao Liu, Yating Wen, Xiangyu Zhang, Yue Shen, Changjiang Zhou, Shi-Tong Zhang, Bing Yang
Summary: In this study, a folding structure was used to achieve pure organic room-temperature phosphorescence, and the rationality of the folding-induced spin-orbit coupling (SOC) enhancement mechanism was verified through experiments. The results showed that the smaller the folding angle, the higher the efficiency of pure organic room-temperature phosphorescence. This study provides a new molecular design strategy for developing efficient pure organic room-temperature phosphorescent materials.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Jean-Francois Dayen, Nikita Konstantinov, Marlene Palluel, Nathalie Daro, Bohdan Kundys, Mohamed Soliman, Guillaume Chastanet, Bernard Doudin
Summary: Research has shown that using a graphene underlayer to reveal light-induced heating can trigger spin transition in molecules, opening up new possibilities for the potential use of spin crossover materials in room temperature optoelectronic applications.
MATERIALS HORIZONS
(2021)
Article
Materials Science, Multidisciplinary
A. J. Wright, M. J. Erickson, D. Bromley, P. A. Crowell, C. Leighton, L. O'Brien
Summary: By correlating spin transport parameters with material, temperature, and field dependencies, the origin of unexpected field enhancement in certain ferromagnet/normal metal pairings in NLSVs has been identified as field quenching of magnetic impurity scattering. This effect was confirmed by agreement with field-dependent Kondo theory. The findings not only address a long-standing mystery, but also highlight a potential systematic underestimation of spin transport parameters, providing a simple means to isolate and quantify this additional relaxation mechanism.
Article
Physics, Multidisciplinary
Po-Hsun Wu, Danru Qu, Yen-Chang Tu, Yin-Ze Lin, C. L. Chein, Ssu-Yen Huang
Summary: This study demonstrates the interplay of pure spin current, spin-polarized current, and spin fluctuation in 3d NixCu1-x. By exploiting the interaction of spin current with spin fluctuation in suitable Ni-Cu alloys, an unprecedentedly high spin Hall angle and spin-dependent thermal transport are achieved, which are of great significance for spintronic applications.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Ya-Ru Wang, Zheng-Chuan Wang, Gang Su
Summary: The spinor Boltzmann equation beyond gradient approximation in a ferromagnetic metal with a single domain wall is derived, along with the charge continuity equation and spin diffusion equation. A generalized spin transfer torque (STT) is obtained using the spin diffusion equation, extending the usual STT to cases beyond gradient approximation and with inhomogeneous current. Numerical calculations are performed for physical observables, and the motion of domain walls and critical electric fields are studied using the Landau-Lifshitz-Gilbert-Slonczewski equation.
Article
Materials Science, Multidisciplinary
V. N. Mantsevich, D. S. Smirnov
Summary: The weak spin-orbit coupling in nonmagnetic semiconductor nanostructures limits the current-induced spin accumulation. However, the Kondo effect provides a possibility to parametrically increase spin polarization. By considering the many-body correlations between a quantum dot and a quantum wire, the current-induced spin accumulation can be enhanced by almost two orders of magnitude at low temperatures, due to the Kondo peak formation and the spin instability caused by strong Coulomb interaction. This effect could be useful for electrically manipulating localized electron spins in quantum dots for quantum applications.
Article
Physics, Applied
A. Yamada, M. Yamada, M. Honda, S. Yamada, K. Sawano, K. Hamaya
Summary: The study reports the highest two-terminal magnetoresistance ratio in semiconductor-based vertical spin-valve devices on a silicon platform. By utilizing Co2FeSi as one of the FM electrodes and a 20-nm-thick Ge intermediate layer, they achieved over 1% two-terminal MR ratios even at room temperature. It was emphasized that Co-based Heusler alloys are effective in obtaining high MR ratios at room temperature in SC-based VSV structures on Si.
APPLIED PHYSICS LETTERS
(2021)
Review
Chemistry, Multidisciplinary
Naihang Zheng, Haoliang Liu, Yu-Jia Zeng
Summary: Growing interest in spintronics and organic materials is driven by advancements in novel information processing technology and low-cost, flexible materials. Organic spintronics has witnessed significant progress in the past two decades due to innovative exploitation of charge-contained spin polarized current. However, less exploration has been done on charge-absent spin angular momentum flow, namely pure spin currents (PSCs), in organic functional solids. This review explores the past research on PSC phenomenon in organic materials, including non-magnetic semiconductors and molecular magnets, highlighting the generation mechanism and experimental observations of PSC, as well as discussing the propagating mechanism in the organic media. Future perspectives on PSC in organic materials are also discussed, focusing on single molecule magnets, complexes for the organic ligands framework, lanthanide metal complexes, organic radicals, and 2D organic magnets.
Article
Physics, Applied
Yiqing Dong, Teng Xu, Wanjun Jiang
Summary: The study demonstrates that spin valve effect driven by current-induced spin-orbit torques can help to achieve electrically controllable and miniaturized two terminal spintronic devices. Spin currents from dual surfaces of the inserted Pt layer can generate spin torques that switch adjacent ferrimagnetic layers, leading to the observation of current-in-plane giant magnetoresistance in a two-terminal device. This research is important for designing miniaturized spintronic devices.
APPLIED PHYSICS LETTERS
(2021)
Article
Materials Science, Multidisciplinary
S. Mojtaba Tabatabaei, David Sanchez, Alfredo Levy Yeyati, Rafael Sanchez
Summary: We discuss a quantum thermal machine that generates power from a thermally driven double quantum dot coupled to normal and superconducting reservoirs. Energy exchange between the dots is mediated by electron-electron interactions. We find that the heat engine efficiency increases with increasing coupling to the superconducting reservoir. The presence of the superconducting gap and the strong energy dependence of the electronic density of states around the gap edges contribute to large efficiencies. The competition between Andreev processes and quasiparticle tunneling is observed in the system. Our results emphasize the importance of both pair tunneling and structured band spectrum for an accurate characterization of the heat engine properties in normal-superconducting coupled dot systems.
Article
Mechanics
S. Hadi Seyedi, Mohsen Zayernouri
Summary: The article introduces a novel autonomously dynamic nonlocal turbulence model for the large eddy simulation of homogeneous isotropic turbulent flows. Through experimental and comparative analysis, it is verified that the model exhibits significant agreement with the actual DNS results in simulating turbulent flows.
Article
Chemistry, Physical
Yaojun Dong, Xixi Tao, Lihua Wang, Yinzhong Wu, Ning Yu, Long Bai, Xuefeng Wang, Xifeng Yang, Yushen Liu
Summary: The study explores the properties of nano-devices based on sawtooth edged graphene nanoribbons, uncovering robust spin-semiconducting properties and a large spin Seebeck coefficient. A new nano-device is proposed which generates a pure spin current through the photogalvanic effect, independent of photon characteristics, due to the symmetry of spatial inversion and anti-symmetry of spin density inversion.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Liupeng Yang, Yaoyu Gu, Lina Chen, Kaiyuan Zhou, Qingwei Fu, Wenqiang Wang, Liyuan Li, Chunjie Yan, Haotian Li, Like Liang, Zishuang Li, Yong Pu, Youwei Du, Ronghua Liu
Summary: The study investigates spin transport in the disordered magnetic amorphous Y3Fe5O12 (a-YIG) and finds no long-distance spin transport, but reveals a weak spin-torque FMR voltage signal in vertical structures. Additionally, an improved interfacial spin-mixing conductance is identified, which can enhance spin-orbit torque efficiency in ferromagnet/heavy metal systems with a disordered magnetic a-YIG buffer layer.
Article
Multidisciplinary Sciences
Zainab Gholami, Farhad Khoeini
Summary: The study investigated the spin-dependent transport properties in hybrid graphene/silicene nanoribbons and found that a pure thermal spin current can be obtained by modulating the temperature, while a negative differential thermoelectric resistance was observed.
SCIENTIFIC REPORTS
(2021)
Article
Physics, Condensed Matter
Minoru Yafuso, Keishi Miyazaki, Yusei Takayama, Sora Obinata, Takashi Kimura
Summary: The static and dynamic magnetization properties of a NiFe/Pt/CoFeB tri-layered film were investigated. It was found that the two ferromagnetic layers separated by a Pt spacer exhibit ferromagnetic coupling even at room temperature. In addition, the damping constant of the NiFe layer was observed to significantly increase with a non-linear power dependence. These unique magnetic features in the NiFe layer can be explained by the weak ferromagnetism induced in the Pt spacer.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Physics, Applied
Riku Iimori, Sora Obinata, Akihiro Mitsuda, Takashi Kimura
Summary: We experimentally investigate the influence of pressure on the spin-charge conversion efficiency in a CoFeB/Pt bilayer system. The results show that the dc voltage spectra systematically increase with increasing pressure, indicating an enhancement of the spin-charge conversion efficiency. This suggests that pressure can be used to modulate the physical constants in spintronic devices.
APPLIED PHYSICS EXPRESS
(2022)
Article
Engineering, Electrical & Electronic
T. Iwahori, K. Mizokami, R. Matsuda, K. Ohnishi, T. Kimura
Summary: We have developed a mesoscopic multi-terminal superconducting Nb strip with a spin injection terminal, and investigated the influence of spin polarization on the relaxation process of quasiparticles in the superconducting Nb. The position dependence of the nonlocal voltage provides the quasiparticle relaxation length. It is found that the relaxation length for spin-polarized quasiparticles shows a 12.5% increase compared to unpolarized quasiparticles. This demonstration opens up a new avenue for utilizing spin current in superconducting devices.
IEEE TRANSACTIONS ON MAGNETICS
(2022)
Article
Physics, Applied
Taisei Ariki, Tatsuya Nomura, Kohei Ohnishi, Takashi Kimura
Summary: We have developed a lateral spin valve and successfully achieved spin injection and detection. By adjusting the relative angle of magnetization, we observed significant modulation of the nonlocal spin accumulation signal. This modulation phenomenon can be explained by the spin absorption effects in the spin resistance model.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Physics, Applied
Xiaomin Cui, Shaojie Hu, Takashi Kimura
Summary: By reducing the lateral dimension of the nonmagnetic spin channel, the spin accumulation signal in lateral spin valves can be effectively enhanced. The temperature dependence of the spin accumulation signal and the influence of thermal spin injection under high bias current are also discussed.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Md Kamruzzaman, Shaojie Hu, Kohei Ohnishi, Takashi Kimura
Summary: This study systematically measures the magneto-thermoelectric voltage induced in a ferromagnetic permalloy nanowire using a laterally configured nanospintronic device. The angular dependence of the magneto-thermoelectric signals are quantitatively explained by the combination of the magneto-Seebeck and anomalous Nernst effects. The contribution of the transverse magneto-Seebeck effect is surprisingly significant in certain probe configurations, indicating the importance of transverse heat flow. These findings demonstrate the usefulness of the magneto-thermoelectric effect for analyzing heat distribution in nanostructured devices.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Yuanlu Tsai, Zhiteng Li, Shaojie Hu
Summary: This article reviews the current developments in atomic layer technology for spintronics, including atomic layer deposition (ALD) and atomic layer etching (ALE). The importance of these techniques in device fabrication is discussed, along with their applications in various materials. The article also compares the critical factors of ALD and ALE and explores the future prospects and challenges of atomic layer technology in spintronics.
Article
Materials Science, Multidisciplinary
Shaojie Hu, Xiaomin Cui, Zengji Yue, Pangpang Wang, Lei Guo, Kohei Ohnishi, Xiaolin Wang, Takashi Kimura
Summary: The magnetic exchange bias (EB) effect is a representative interlayer magnetic coupling phenomenon and has various technological applications. This study investigates the positive exchange-biased anomalous Hall effect in FeGeTe vdW nano-flakes and proposes that the coexistence of stable and frustrated surface magnetization can modify the interface coupling energy density, leading to an unusual EB effect.
Article
Engineering, Electrical & Electronic
Shuhan Liu, Shaojie Hu
Summary: This study investigates the heat contribution of magnetic tunnel junctions in parallel and antiparallel states through tunneling spin scattering. The results show a significant temperature increase of 23.2% from parallel to antiparallel, which is even more significant than the heating asymmetry caused by different current directions. Moreover, the study confirms that the enhancement of temperature gradient plays a significant role in the extra thermal spin-transfer torque.
IEEE TRANSACTIONS ON MAGNETICS
(2022)
Article
Multidisciplinary Sciences
Sora Obinata, Riku Iimori, Kohei Ohnishi, Takashi Kimura
Summary: In this study, the contribution of dynamical spin injection in a ferromagnetic resonance is investigated, and the heating effect is pointed out as an important factor. By combining proper spin pumping and heat-flow control, efficient dynamical spin injection can be achieved.
SCIENTIFIC REPORTS
(2022)
Article
Chemistry, Multidisciplinary
Shaojie Hu, Xiaomin Cui, Kang Wang, Satoshi Yakata, Takashi Kimura
Summary: In this study, the resonance property of a magnetic vortex contained within a micron-sized square Py dot was investigated using an amplitude-modulated magnetic field excitation technique. The resonant spectra showed significant modulation as the external magnetic field changed. Micromagnetic simulations confirmed that this behavior was due to the unusual resistance change depending on the vortex core center position. Furthermore, the power dependence of the anti-Lorentzian-like spectra revealed a persistent coexistence of peak and dip.
Article
Chemistry, Physical
Po-Chun Chang, Shi-Yu Liu, Hung-Lin Lin, Shaojie Hu, Takashi Kimura, Fang-Yuh Lo, Wen-Chin Lin
Summary: Yttrium iron garnet (YIG) is a crucial ferromagnetic insulator for transporting pure spin, and the exchange coupling at the antiferromagnet/ferromagnet (AFM/FM) interface allows for engineering spintronic devices. This study demonstrates the observation of room temperature positive exchange bias (RT-PEB) by fabricating further oxidized CoO on YIG. The RT-PEB is explained by aligning the CoO interface spins with an applied magnetic field and coupling them antiparallelly to YIG. These findings offer a pathway to reversibly modulate the interfacial magnetic properties of insulating AFM/FM heterostructures.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
