Article
Multidisciplinary Sciences
Machiel Flokstra, Rhea Stewart, Chi-Ming Yim, Christopher Trainer, Peter Wahl, David Miller, Nathan Satchell, Gavin Burnell, Hubertus Luetkens, Thomas Prokscha, Andreas Suter, Elvezio Morenzoni, Irina V. Bobkova, Alexander M. Bobkov, Stephen Lee
Summary: The study found that spin-triplet pair correlations can be generated in a simple structure without the use of ferromagnetic elements. By observing the local electronic and magnetic properties, it was confirmed that the spin-orbit generated magnetization comes from equal-spin pairs rather than their orbital motion.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Takahiro Kobayashi, Yuichiro Toichi, Koichiro Yaji, Yoshitaka Nakata, Yuchi Yaoita, Mutsuki Iwaoka, Mariko Koga, Yituo Zhang, Jun Fujii, Shimpei Ono, Yasmine Sassa, Yasuo Yoshida, Yukio Hasegawa, Fumio Komori, Shik Shin, Satoru Ichinokura, Ryota Akiyama, Shuji Hasegawa, Tatsuya Shishidou, Michael Weinert, Kazuyuki Sakamoto
Summary: The interplay of spin-orbit coupling and crystal symmetry can generate spin-polarized bands in materials only a few atomic layers thick, potentially leading to unprecedented physical properties. In bilayer materials with global inversion symmetry, locally broken inversion symmetry can generate degenerate spin-polarized bands. This study demonstrates the revelation of hidden spins in a Tl bilayer crystal on Ag(111) with sizable lattice mismatch, resulting in a novel band splitting in both spin and space.
Article
Physics, Multidisciplinary
Chunli Huang, Nemin Wei, Wei Qin, Allan H. MacDonald
Summary: The study presents a theory of superconductivity in twisted bilayer graphene, where attraction is generated between electrons on the same honeycomb sublattice near a sublattice polarization instability, leading to spin-polarized valley singlet Cooper pairs. Superconductivity occurs over a wide range of filling fraction, and can be suppressed by controlling sublattice polarizability or moire band filling to favor valley polarization.
PHYSICAL REVIEW LETTERS
(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
Nanoscience & Nanotechnology
Talieh S. Ghiasi, Alexey A. Kaverzin, Avalon H. Dismukes, Dennis K. de Wal, Xavier Roy, Bart J. van Wees
Summary: The coupling of bilayer graphene with the 2D interlayer antiferromagnetic CrSBr enables the active generation of spin currents in graphene, benefiting ultracompact spintronic devices. The strong spin-charge coupling in graphene and the high sensitivity of spin transport to the adjacent antiferromagnet's magnetization allow for the read-out of a single magnetic sublattice.
NATURE NANOTECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Lan -Ting Shi, Jian-Guo Si, Akun Liang, Robin Turnbull, Peng-Fei Liu, Bao-Tian Wang
Summary: Inspired by the AV3Sb5 family, the topological and superconducting properties of bilayer kagome metal materials YT6Sn6 (T=V, Nb, Ta) were investigated using first-principles calculations. These materials exhibit stability, Z2 topological classification, and weak superconductivity. The predicted superconducting critical temperatures (Tc) for YV6Sn6, YNb6Sn6, and YTa6Sn6 are 0.65 K, 1.17 K, and 0.89 K, respectively. The coexistence of nontrivial topological properties and superconductivity in these bilayer kagome systems is significant for studying the relationship between different physical properties and designing new topological superconductors.
Article
Materials Science, Multidisciplinary
S. Leith, J. Qiao, M. Vogel, E. Seiler, R. Ries, Y. Li, C. Wiktor, J. Mueller, Y. Sakalli, B. Butz, X. Jiang
Summary: The use of energetic condensation techniques, such as HiPIMS, has the potential to improve the superconducting performance of coated Cu cavities by producing bulk-like Nb thin films. However, a deeper understanding of the effects of deposition parameters, film properties, and superconducting performance is needed. This study explores the effects of different HiPIMS deposition parameters on the morphological, crystallographic, and superconducting properties of Nb thin films deposited onto electropolished Cu substrates. Higher duty cycles, surface smoothness, and transition zones in film growth are observed.
Article
Physics, Applied
Apoorva Verma, Mandeep Kaur, T. D. Senguttuvan, Anurag Gupta
Summary: The magnetic NiFe artificial spin ice (ASI) has a significant influence on the transport properties of superconducting Nb, leading to an increase in resistivity, a decrease in superconducting transition temperature, disappearance of surface sheath superconductivity, and suppression of perpendicular upper critical field throughout the temperature range. The results are attributed to the thin film nature of the samples, geometrically frustrated magnetism of ASI, and the proximity between the magnetic NiFe-ASI and superconducting Nb at the interface.
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM
(2021)
Article
Physics, Condensed Matter
Ekta Bhatia, Zainab Hussain, V. Raghavendra Reddy, Zoe H. Barber, Kartik Senapati
Summary: This report investigates the additional resistance caused by scattering of electrons passing through ferromagnetic domain walls, as well as the possible spin-triplet supercurrent conversion effect in these domain walls. Experimental results indicate that in the superconducting state, the transport current may induce spin-triplet correlations in the ferromagnetic domain walls.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Chemistry, Multidisciplinary
Taiyu An, Bin Cui, Liang Liu, Mingfang Zhang, Fufu Liu, Weikang Liu, Jihao Xie, Xue Ren, Ruiyue Chu, Bin Cheng, Changjun Jiang, Jifan Hu
Summary: It is found that spin current with strong out-of-plane polarization component can be generated and transmitted in Ni81Fe19/Cu-CuOx bilayer through sideways and top oxidizations. The spin currents consisting of both out-of-plane polarization (sigma(z)) and in-plane polarization (sigma(y)) induced by spin-vorticity coupling can enhance the charge-to-spin current conversion efficiency. This spin current is closely related to the lateral oxidization gradient and can be controlled by changing the temperatures and times of annealing. These findings provide a novel degree of freedom to produce and control spin current in spintronic devices.
ADVANCED MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Daniel Andrew Turner, O. B. Malyshev, G. Burt, E. Seiler, R. Ries, A. Medvids, P. Onufrijevs, R. Valizadeh, A. Sublet, C. Pira, E. Chyhyrynets, M. Vogel, S. Leith, T. Junginger
Summary: Bulk Nb is the common material for SRF cavities, but sputtering thin Nb films onto Cu cavities has the potential to improve their performance. However, issues arise, such as the quality of the Cu surface affecting the quality of the deposited Nb. One approach is to treat the Nb surface with a laser to improve its magnetic field and superconducting properties. Experimental results show that the laser treatment can increase the magnetic field penetration, suggesting potential improvement in Nb coated RF cavities.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Materials Science, Multidisciplinary
Michael Barth, Jacob Fuchs, Denis Kochan
Summary: This study investigates the interplay between spectral and transport properties in bilayer graphene and s-wave superconductors using Green's function analytical methods and numerical simulations. The results reveal unique superconducting signatures that differentiate between resonant and off-resonant regimes, providing important insights into the behavior of bilayer graphene and other functionalized superconductors.
Article
Physics, Applied
Sora Obinata, Kohei Ohnishi, Takashi Kimura
Summary: An effective detection structure for dynamical spin injection in a ferromagnetic/nonmagnetic metal bilayer has been developed, showing clear detection of a highly symmetric signal. The angular dependence of the signal amplitude confirms the observation of the inverse spin Hall effect. The importance of eddy currents in inducing spin-rectified signals from the ferromagnetic layer is also emphasized.
APPLIED PHYSICS LETTERS
(2021)
Article
Materials Science, Ceramics
Hao Jin, Yun Xiao, XiaoYao Nong, EnFei Zhou, He Lin, Xifeng Pan
Summary: A roll-die drawing method is proposed to fabricate long-length and uniform shape composite tapes. The magnetic critical current density Jc of the Sr1-xKxFe2As2 tape reaches up to 4.7 x 10(4) A/cm(2) at 5 K and 5 T. The transport Jc of the tape decreases to about 2.0 x 10(3) A/cm(2) at 4.2 K and 10 T, indicating weak intergranular coupling.
CERAMICS INTERNATIONAL
(2023)
Article
Multidisciplinary Sciences
Baochun Wu, Ruge Quhe, Jie Yang, Shiqi Liu, Junjie Shi, Jing Lu, Honglin Du
Summary: This study designs spin devices based on bilayer 2H-VSe2 and investigates their spin-resolved transport properties, revealing a high spin-filter efficiency of 99% and a significant conductance on-off ratio. This indicates the promising performance of bilayer 2H-VSe2 in spintronic devices.
ADVANCED THEORY AND SIMULATIONS
(2021)
Article
Chemistry, Physical
Po-Chun Chang, Venkata Ramana Mudinepalli, Shi-Yu Liu, Hung-Lin Lin, Chuan-Che Hsu, Yu-Tso Liao, Sora Obinata, Takashi Kimura, Ming-Yau Chern, Fang-Yuh Lo, Wen-Chin Lin
Summary: The study observed magnetic modulation on YIG by depositing a CoOx top layer. The nonuniform stoichiometric distribution in the CoOx layer and the magnetic coupling effects between ferromagnetic CoOx and antiferromagnetic CoO were confirmed to be the origin of the various magnetic behaviors observed. Ferromagnetic resonance measurements also demonstrated considerable magnetic coupling effect on the dynamic magnetism of the YIG.
JOURNAL OF ALLOYS AND COMPOUNDS
(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
Engineering, Electrical & Electronic
S. Obinata, R. Iimori, K. Ohnishi, T. Kimura
Summary: In this study, we investigated the dynamic spin injection in a CoFeB/Pt/CoFeB trilayered structure and observed a clear voltage change attributed to the inverse spin Hall effect. By considering the thermal spin injection during ferromagnetic resonance, we were able to quantitatively explain the observed signal. This innovative demonstration highlights the significant contribution of FMR heating in dynamic spin injection.
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
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
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.
