Article
Multidisciplinary Sciences
T. Kikkawa, D. Reitz, H. Ito, T. Makiuchi, T. Sugimoto, K. Tsunekawa, S. Daimon, K. Oyanagi, R. Ramos, S. Takahashi, Y. Shiomi, Y. Tserkovnyak, E. Saitoh
Summary: The article reports on a nuclear thermoelectric effect caused by nuclear spins in a solid, with low-temperature thermoelectric signals observed down to 100mK. The experiment and theoretical calculations demonstrate the potential for exploring thermoelectric science and technologies at ultralow temperatures.
NATURE COMMUNICATIONS
(2021)
Review
Optics
Minkyung Kim, Younghwan Yang, Dasol Lee, Yeseul Kim, Hongyoon Kim, Junsuk Rho
Summary: This article reviews the principle, recent developments, and applications of the spin Hall effect of light (SHEL). The theoretical description of the SHEL is provided, along with a comprehensive review of recent studies and applications. The future direction and prospects of the SHEL are also discussed.
LASER & PHOTONICS REVIEWS
(2023)
Article
Physics, Applied
P. Jimenez-Cavero, I. Lucas, D. Bugallo, C. Lopez-Bueno, R. Ramos, P. A. Algarabel, M. R. Ibarra, F. Rivadulla, L. Morellon
Summary: By studying the dependence of the inverse spin Hall voltage and thermal conductivity on magnetic layer thickness, the separate contributions of bulk and interfacial sources to the thermally excited magnon spin current in the spin Seebeck effect were identified. The modulation of thermal drops relative magnitude by magnetic layer thickness, along with the determination of the thermal magnon accumulation length scale in maghemite, revealed that bulk magnon accumulation dominates the spin Seebeck effect but the interfacial component is non-negligible.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Lin Huang, Yongjian Zhou, Hongsong Qiu, Hua Bai, Chong Chen, Weichao Yu, Liyang Liao, Tingwen Guo, Feng Pan, Biaobing Jin, Cheng Song
Summary: The inverse spin Hall effect (ISHE) has been investigated in Mn2Au/[Co/Pd] heterostructures, showing that the direction of the Neel vector has a significant impact on the ISHE signal. This finding not only expands the study of the Hall effect, but also enhances the flexibility of antiferromagnetic spintronics.
ADVANCED MATERIALS
(2022)
Article
Chemistry, Physical
Won-Yong Lee, Min-Sung Kang, Gil-Sung Kim, No-Won Park, Jae Won Choi, Eiji Saitoh, Sang-Kwon Lee
Summary: The study investigates the presence of asymmetric in-plane temperature contribution in longitudinal spin Seebeck effect (LSSE) measurements, where an unintended in-plane Seebeck effect is observed in the Pt/WSe2/YIG structure due to asymmetric lateral temperature distribution. The modified in-plane Seebeck factor and the effective in- and out-of-plane temperature differences ratio indicate a substantially high in-plane temperature contribution in LSSE measurements using two-dimensional interlayers in a Pt/YIG structure.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Multidisciplinary
Amit Chanda, Christian Holzmann, Noah Schulz, Johannes Seyd, Manfred Albrecht, Manh-Huong Phan, Hari Srikanth
Summary: The authors systematically investigated the longitudinal spin Seebeck effect (LSSE) in a GGG/GdIG/Pt film series with in-plane magnetic easy axis and compensation temperature (T-Comp), finding a strong correlation between LSSE signal and orientation of magnetic easy axis. They also demonstrated the possibility to tune LSSE through effective anisotropy.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Review
Chemistry, Multidisciplinary
Thomas G. W. Edwardson, Mikail D. Levasseur, Stephan Tetter, Angela Steinauer, Mao Hori, Donald Hilvert
Summary: This article reviews the efforts to repurpose various protein cages as vaccines, drug delivery vehicles, imaging agents, etc., highlighting the importance of understanding the principles underlying construction, function, and evolution in protein engineering.
Article
Nanoscience & Nanotechnology
Won-Yong Lee, Min-Sung Kang, Gil-Sung Kim, No-Won Park, Kwang-Yong Choi, Chinh Tam Le, Mamoon Ur Rashid, Eiji Saitoh, Yong Soo Kim, Sang-Kwon Lee
Summary: The introduction of a monolayer tungsten diselenide (ML WSe2) interlayer in the Pt/YIG bilayer system increases the longitudinal SSE (LSSE) voltage significantly by enhancing spin accumulation in the Pt layer. The spin fluctuation in ML WSe2 amplifies spin current transmission, leading to a substantial improvement in thermopower. Additionally, the induced ferromagnetic properties of the ML WSe2 flakes boost the LSSE voltage.
ACS APPLIED MATERIALS & INTERFACES
(2021)
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.
Article
Physics, Multidisciplinary
Jinsong Xu, Jiaming He, J-S Zhou, Danru Qu, Ssu-Yen Huang, C. L. Chien
Summary: In this study, we observed the existence of a vector spin Seebeck effect in a noncollinear antiferromagnet and found that this effect can be controlled by a small magnetic field. Noncollinear antiferromagnets provide a new avenue for exploring spin phenomena, compared to collinear antiferromagnets.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Jinqiang Zhang, Haijun Chen, Xiaoguang Duan, Hongqi Sun, Shaobin Wang
Summary: Photothermal catalysis is an innovative approach that integrates photochemical and thermocatalytic processes to efficiently utilize full-spectrum sunlight for chemical reactions. This review comprehensively explores the fundamentals, classification, design principles, and applications of photothermal catalysis, and discusses future opportunities and challenges.
Article
Nanoscience & Nanotechnology
Won-Yong Lee, No-Won Park, Min-Sung Kang, Gil-Sung Kim, Young-Gui Yoon, Suheon Lee, Kwang-Yong Choi, Keun Soo Kim, Jin-Hyuk Kim, Maeng-Je Seong, Takashi Kikkawa, Eiji Saitoh, Sang-Kwon Lee
Summary: The study revealed the impact of intrinsic YIG surface magnetic anisotropy on the spin Seebeck effect. By introducing a graphene interlayer, evidence for extrinsic surface magnetic anisotropy was observed, providing insight into new physics of spin transport.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Review
Chemistry, Multidisciplinary
Jaemin Min, Dipankar Barpuzary, Hyeonseong Ham, Gyeong-Chan Kang, Moon Jeong Park
Summary: Charged block copolymers with well-ordered structures can effectively control self-assembly and ion diffusion behavior for enhanced ionic conductivity. By tuning the nanostructures and ionic interactions, interconnected ionic channels are promoted to create efficient ion conduction pathways in various morphologies, leading to high-performance materials for next-generation electrochemical devices and soft robotics.
ACCOUNTS OF CHEMICAL RESEARCH
(2021)
Review
Chemistry, Multidisciplinary
Jin-Tao Ren, Lei Chen, Hao-Yu Wang, Zhong-Yong Yuan
Summary: This review provides a comprehensive summary of recent advances in the synthesis strategies, design principles, and characterization technologies of high entropy alloys (HEAs), and their applications in various electrocatalytic conversion reactions. By covering these topics comprehensively, the review aims to elucidate the intricacies of active sites, constituent element interactions, and reaction mechanisms associated with HEAs.
CHEMICAL SOCIETY REVIEWS
(2023)
Article
Chemistry, Multidisciplinary
Yujie Hu, Shanshan Liu, Jing Huang, Xingxing Li, Qunxiang Li
Summary: Researchers propose using bipolar magnetic molecules as the core component of single-molecule devices to generate pure spin currents through the spin Seebeck effect with applied temperature gradient. The spin Seebeck coefficient can also be modulated over a wide range by applying an external gate voltage.
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
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
Sohei Horibe, Hiroki Shimizu, Koujiro Hoshi, Takahiko Makiuchi, Tomosato Hioki, Eiji Saitoh
Summary: Parametric oscillation occurs when the resonance frequency of an oscillator is periodically modulated. Owing to time-reversal symmetry breaking in magnets, nonreciprocal magnons can be parametrically excited when spatial-inversion symmetry breaking is provided. We demonstrate switching on and off the magnon parametric oscillation by reversing the external field direction applied to a Y3Fe5O12 micro-structured film. The result originates from the nonreciprocity of surface mode magnons, leading to field-direction dependence of the magnon accumulation under nonuniform microwave pumping. Our numerical calculation well reproduces the experimental result.
APPLIED PHYSICS EXPRESS
(2023)
Article
Physics, Applied
Weinan Zhou, Asuka Miura, Takamasa Hirai, Yuya Sakuraba, Ken-ichi Uchida
Summary: Seebeck-driven transverse thermoelectric generation (STTG) was investigated in magnetic/thermoelectric hybrid materials. The transverse thermopower in a ferromagnetic Co2MnGa/thermoelectric n-type Si hybrid bulk material reached 16.0 lV/K at room temperature, which is much larger than the anomalous Nernst coefficient of the Co2MnGa slab (6.8 lV/K). Although the transverse thermopower is smaller compared to thin-film-based hybrid materials, the hybrid bulk materials exhibit larger electrical power due to their small internal resistance. This study confirms the validity of STTG in bulk materials and highlights its potential as a thermal energy harvester.
APPLIED PHYSICS LETTERS
(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
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
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.
