Article
Physics, Multidisciplinary
Kouki Nakata, Kei Suzuki
Summary: Quantum fluctuations, key concepts of quantum mechanics, induce a zero-point energy shift known as the Casimir effect. This phenomenon has attracted attention in various fields, from elementary particle physics to condensed matter physics and photonics. While yttrium iron garnet (YIG) has been extensively studied for spintronics, the application of the Casimir effect to ferrimagnetic thin films has not been explored enough. In this study, using lattice field theory, we investigate the Casimir effect on magnons in insulating magnets and find that it can arise in ferrimagnetic YIG thin films. Our results suggest that YIG can serve as a promising platform for Casimir engineering in magnon-based spintronics.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Olga Borovkova, Mikhail A. Kozhaev, Hisham Hashim, Anna A. Kolosova, Andrey N. Kalish, Sarkis A. Dagesyan, Alexander N. Shaposhnikov, Vladimir N. Berzhansky, Vladimir Belotelov
Summary: Spatial symmetry breaking in magnetoplasmonic systems leads to magneto optical effects that are not allowed in symmetric structures. The transverse magneto-photonic transmission effect (TMPTE) occurs as a result of the inequality between the forward and backward surface plasmon polariton waves at the metal/dielectric interface in non-symmetric plasmonic gratings.
OPTICAL MATERIALS EXPRESS
(2022)
Article
Materials Science, Multidisciplinary
Pieter M. Gunnink, Rembert A. Duine, Andreas Rueckriegel
Summary: In this study, we derived the anomalous Hall contributions from dipolar interactions in magnetic insulators, revealing the role of magnons as carriers of angular momentum in diffusive spin transport. We calculated the anomalous and magnon spin conductivities for yttrium iron garnet (YIG) thin films, showing a finite anomalous Hall conductivity for a magnetic field perpendicular to the film. Moreover, we demonstrated the possibility of electrical detection and injection of spin, predicting experimentally measurable Hall coefficients for a variety of temperatures and magnetic field strengths.
Article
Physics, Multidisciplinary
M. A. Yavorsky, M. A. Kozhaev, A. Yu. Fedorov, D. V. Vikulin, E. V. Barshak, V. N. Berzhansky, S. D. Lyashko, P. O. Kapralov, V. I. Belotelov
Summary: We experimentally demonstrate the topological Faraday effect caused by the orbital angular momentum of light. The Faraday effect for an optical vortex beam passing through a transparent magnetic dielectric film is different from that for a plane wave. The additional contribution to the Faraday rotation depends linearly on the topological charge and radial number of the beam. These findings highlight the importance of using optical vortex beams for studying magnetically ordered materials.
PHYSICAL REVIEW LETTERS
(2023)
Article
Optics
Yi-Lei Li, Ding Zhang, Min Luo, Qing-Hui Yang, Fei Fan, Sheng-Jiang Chang, Qi-Ye Wen
Summary: The magneto-optical Faraday response of bismuth-gadolinium-substituted rare-earth iron garnet at terahertz frequencies showed high transmittance and Faraday rotation angle at certain frequencies, with magnetically tunable, non-reciprocal properties that can be used for terahertz devices.
Article
Chemistry, Physical
Jonathan Schmidt, Hai-Chen Wang, Georg Schmidt, Miguel A. L. Marques
Summary: Garnets have important applications in modern technologies, but limited exploration has been done beyond oxide garnets. To find new garnets, researchers combine graph neural networks with high-throughput calculations, discovering over 600 ternary garnets. The electronic structure and the relationship between the electronic band gap and charge balance are analyzed.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Chemistry, Physical
Chen Kang, Tao Wang, Changjun Jiang, Kun Chen, Guozhi Chai
Summary: This study investigated the giant magneto-impedance (GMI) effect on ferrimagnetic insulator yttrium iron garnet (YIG) films and spheres, highlighting the significant role of ferromagnetic resonance effect. The results showed distinct impedance variations in the transmission line loaded with single crystalline YIG samples depending on the external magnetic field, indicating a substantial GMI effect. The maximum GMI ratio reached 256% with a corresponding magnetic response of 8.8%/Oe, suggesting the potential use of single crystalline YIG films in chip-scale magnetic sensors.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Physics, Applied
Jing Ming Liang, Xu Wen Zhao, Yu Kuai Liu, Pei Gen Li, Sheung Mei Ng, Hon Fai Wong, Wang Fai Cheng, Yan Zhou, Ji Yan Dai, Chee Leung Mak, Chi Wah Leung
Summary: The magnetization reversal of terbium iron garnet (TbIG) thin films at different temperatures was studied using anomalous Hall effect measurements. The compensation temperature (T-comp) of TbIG thin films was determined and the effect of film thickness on T-comp was investigated. The results showed that T-comp increases with decreasing film thickness. Two possible origins for this behavior were proposed, including interfacial element diffusion and strain effects between TbIG films and Gd3Ga5O12 substrates. These findings have implications for the study of spintronic devices based on ultrathin rare-earth iron garnet thin films.
APPLIED PHYSICS LETTERS
(2023)
Article
Optics
Olga Borovkova, Vladimir Belotelov
Summary: In this study, a magnetic photonic crystal (MPC) nanostructure with a gradient thickness of the magnetic layer is proposed, which allows on-the-fly adjustment of optical and magneto-optical properties. The spectral position of the defect mode resonance in the bandgap of transmission and magneto-optical spectra can be tuned by spatial displacement of the input beam, while the resonance width in both optical and magneto-optical spectra can be controlled by varying the diameter of the input beam or its focus.
Article
Materials Science, Multidisciplinary
Rico Schmidt, Piet W. Brouwer
Summary: This study evaluates the magnetic-field dependence of the spin Seebeck effect in a ferromagnetic insulator at low temperatures using a simplified microscopic model. The research shows that singular features observed at low temperatures are independent of the relative strength of magnon and phonon scattering.
Article
Quantum Science & Technology
Tomoki Hirosawa, Alexander Mook, Jelena Klinovaja, Daniel Loss
Summary: This research proposes a theory of magnetoelectric magnon-photon coupling, reveals the electrical activity of skyrmion eigenmodes, and predicts a cavity-induced magnon-magnon coupling, suggesting potential applications in quantum information processing.
Article
Chemistry, Inorganic & Nuclear
Joanna Milam-Guerrero, Michelle Zheng, Nicole R. Spence, Mario Falsaperna, Stuart Calder, Saul Lapidus, Paul J. Saines, Brent C. Melot
Summary: The study reveals that despite well-pronounced magnetic transitions at low temperatures in both iron-based garnets, there is evidence of diffuse magnetic scattering due to competition within the tetrahedral sites, resulting in a complex noncollinear magnetic structure with a mixture of ferro- and antiferromagnetic interactions.
INORGANIC CHEMISTRY
(2021)
Article
Multidisciplinary Sciences
A. E. Khramova, M. Kobecki, I. A. Akimov, I. Savochkin, M. A. Kozhaev, A. N. Shaposhnikov, V. N. Berzhansky, A. K. Zvezdin, M. Bayer, V. Belotelov
Summary: This study demonstrates a new method for tuning the excitation of different spin wave modes in magnetic microdisks. By using a high repetition rate of laser pulses, an interplay between spin wave resonances in the frequency and momentum domains is established. Additionally, a switching between volume and surface spin waves is achieved through small variations of the external magnetic field.
SCIENTIFIC REPORTS
(2022)
Article
Materials Science, Multidisciplinary
Sanchar Sharma, Victor A. S. V. Bittencourt, Silvia Viola Kusminskiy
Summary: We propose a protocol to generate arbitrary magnetization quantum states in a magnet and numerically evaluate its effectiveness. The protocol involves exciting a frequency-tunable superconducting transmon and transferring the excitations to the magnet, with counter pulses applied to correct for leakage. The protocol allows for the generation of high fidelity magnon states.
JOURNAL OF PHYSICS-MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
E. Almpanis, N. Papanikolaou, N. Stefanou
Summary: This study investigates magnon-mediated optical transitions in micrometer-sized YIG particles, finding that their engineered shape anisotropy leads to high-quality-factor Mie resonances in the infrared spectrum. As a result, photon-magnon coupling strengths can be significantly enhanced compared to submillimeter YIG spheres.
Article
Physics, Multidisciplinary
Aki Kitaori, Naoya Kanazawa, Takanori Kida, Yasuo Narumi, Masayuki Hagiwara, Koichi Kindo, Tetsuya Takeuchi, Ai Nakamura, Dai Aoki, Yoshinori Haga, Yoshio Kaneko, Yoshinori Tokura, Yoshichika O. Nuki
Summary: We have successfully grown single crystalline Tb5Sb3 with a hexagonal structure, which exhibits complex spiral magnetic structures with changing temperature. Specific heat and magnetization measurements revealed one clear magnetic transition at 133 K. The magnetic structure is oriented in the hexagonal basal plane with a hard axis corresponding to the [0001] direction. Below 50 K, the magnetic structure undergoes a transformation, leading to a rapid decrease in magnetic susceptibility for H II [1010] and a kink behavior in low-field magnetization, while showing hysteresis in the magnetization curve.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2023)
Letter
Physics, Multidisciplinary
Minoru Kawamura, Masataka Mogi, Ryutaro Yoshimi, Takahiro Morimoto, Kei S. Takahashi, Atsushi Tsukazaki, Naoto Nagaosa, Masashi Kawasaki, Yoshinori Tokura
Summary: Adiabatic charge pumping is observed in a thin-film magnetic heterostructure of topological insulators, confirming the theoretical prediction of topological magnetoelectric effect. The pumped charge is proportional to the surface Hall conductivity, providing clues for its direct observation.
Article
Physics, Multidisciplinary
H. Takagi, R. Takagi, S. Minami, T. Nomoto, K. Ohishi, M. -t. Suzuki, Y. Yanagi, M. Hirayama, N. D. Khanh, K. Karube, H. Saito, D. Hashizume, R. Kiyanagi, Y. Tokura, R. Arita, T. Nakajima, S. Seki
Summary: The spontaneous topological Hall effect in triangular lattice compounds CoTa3S6 and CoNb3S6 is experimentally demonstrated, combining non-coplanar antiferromagnetic order with finite scalar spin chirality in the absence of a magnetic field. These compounds exhibit unconventionally large spontaneous Hall effects despite their small net magnetization, and the mechanism behind this phenomena is explained by the topological Hall effect associated with scalar spin chirality. The results suggest that the scalar spin chirality mechanism offers a promising route for the realization of a giant spontaneous Hall response in compensated antiferromagnets.
Article
Physics, Multidisciplinary
T. Nomura, X. -X. Zhang, R. Takagi, K. Karube, A. Kikkawa, Y. Taguchi, Y. Tokura, S. Zherlitsyn, Y. Kohama, S. Seki
Summary: The nonreciprocal acoustic properties of a room-temperature ferromagnet Co9Zn9Mn2 unveil the phonon magnetochiral effect close to room temperature. In contrast to the insulating Cu2OSeO3, the nonreciprocity in this metallic compound is enhanced at higher temperatures and observed up to 250 K. Ultrasound and microwave-spectroscopy experiments suggest that the magnitude of the phonon magnetochiral effect mostly depends on the Gilbert damping of Co9Zn9Mn2, which increases at low temperatures and hinders the magnon-phonon hybridization. It is also proposed that the phonon nonreciprocity can be further enhanced by engineering the magnon band of materials.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Kamil K. Kolincio, Max Hirschberger, Jan Masell, Taka-hisa Arima, Naoto Nagaosa, Yoshinori Tokura
Summary: Dynamical spin fluctuations in magnets can be influenced by lattice geometry, leading to chiral spin fluctuations and fluctuation-related transport anomalies. This study focuses on the crucial role of lattice geometry on chiral spin fluctuations and the quantum-mechanical phase of conduction electrons. Experimental results and Monte Carlo calculations suggest that lattices with dissimilar plaquettes exhibit the most promising Berry phase phenomena in paramagnets.
PHYSICAL REVIEW LETTERS
(2023)
Article
Multidisciplinary Sciences
Keisuke Matsuura, Yo Nishizawa, Markus Kriener, Takashi Kurumaji, Hiroshi Oike, Yoshinori Tokura, Fumitaka Kagawa
Summary: In some materials, the equilibrium phase-transition line is concealed by the hysteresis region associated with field-induced first-order transitions (FOTs). Phase diagrams are essential in material science, as they provide comprehensive information about thermodynamic quantities. However, determining the equilibrium phase-transition line in a field-induced FOT is challenging, especially in the presence of large hysteresis.
SCIENTIFIC REPORTS
(2023)
Article
Nanoscience & Nanotechnology
N. Takahara, K. S. Takahashi, K. Maruhashi, Y. Tokura, M. Kawasaki
Summary: EuTiO3 (ETO) is a unique magnetic semiconductor with a large localized magnetic moment of Eu2+. By doping high-mobility electrons in the conduction band, peculiar magnetotransport properties have been observed. In this study, the physical properties of high quality ETO films with La3+ or Gd3+ donors grown on nearly lattice matched substrates are examined. These transport properties provide a deeper understanding of the band structure topology in high-mobility, magnetic oxide semiconductors.
Article
Multidisciplinary Sciences
Yoshihiro D. Kato, Yoshihiro Okamura, Max Hirschberger, Yoshinori Tokura, Youtarou Takahashi
Summary: The study reveals the magneto-optical Kerr effect (MOKE) induced by the formation of magnetic skyrmions in Gd2PdSi3, referred to as topological MOKE. The presence of skyrmions leads to a significant enhancement of the optical rotation, exemplifying the light-skyrmion interaction arising from the emergent gauge field. The findings pave the way for photonic technology based on skyrmionics.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Shunsuke Kitou, Yoshio Kaneko, Yuiga Nakamura, Kunihisa Sugimoto, Yusuke Nomura, Ryotaro Arita, Yoshinori Tokura, Hiroshi Sawa, Taka-hisa Arima
Summary: By performing core differential Fourier synthesis (CDFS) analysis of high-energy X-ray diffraction data, we directly observe the distribution state of Mo 4d orbital electrons in a pyrochlore-type oxide Nd2Mo2O7 at subangstrom resolution. The obtained valence electron density (VED) distribution confirms the Mo4+ 4d2 orbital state, and a dip in the radial profile indicates a node of the 4d wave function. The VED distribution around the Nd site is attributed to the hybridization of neighboring O 2p with Nd 6s/6p/5d orbitals and the anisotropic Nd3+ 4f3 electrons, which cannot be explained by simple j-j or LS coupling models. This study demonstrates the usefulness of CDFS analysis in investigating orbital states in crystalline materials.
Article
Materials Science, Multidisciplinary
Y. H. Zhuang, H. W. Liu, Y. H. Li, Y. M. Chang, T. Kurumaji, Y. Tokura, Y. M. Sheu
Summary: This study reveals the crucial role of crystal-field excitations involving spin-flip transitions in controlling switchable optomagnet effects in antiferromagnetic (Fe0.875Zn0.125)2Mo3O8. The photoinduced magnetization does not occur until the flipped spins are in excited states that frustrate the balanced spin moments, and it only starts to grow from a zero moment after the ultrashort pulses disappear. Through Kerr-effect microscopy and application of magnetic fields, the study distinguishes between photoinduced switchable magnetization and nonswitchable demagnetization. The experimental designs uncover essential factors for the development of antiferromagnetic memory devices using insulating oxides.
Article
Materials Science, Multidisciplinary
M. Ogino, Y. Kaneko, Y. Tokura, Y. Takahashi
Summary: We investigate the nonreciprocity of photons caused by enhanced dynamical magnetoelectric (ME) coupling in multiferroic perovskite manganites. The correlation between the optical ME effects and the order parameters is examined by changing the composition of the manganites. Nonreciprocal directional dichroism and gyrotropic birefringence are demonstrated in different spin-cycloidal phases, and their magnitudes show deviations from the relevant coupled order parameters.
Article
Materials Science, Multidisciplinary
Jiwon Ju, Hiraku Saito, Takashi Kurumaji, Max Hirschberger, Akiko Kikkawa, Yasujiro Taguchi, Taka-hisa Arima, Yoshinori Tokura, Taro Nakajima
Summary: We investigated the magnetic structures of Gd2PdSi3, a centrosymmetric skyrmion material, using polarized neutron scattering. Our results confirmed the elliptic screw-type magnetic modulation in zero field with a propagation vector of (q, 0, 0). As the temperature increases, the system undergoes a magnetic phase transition while maintaining the incommensurate q-vector of (q, 0, 0). In the ground state, the system contains equal fractions of left-handed and right-handed screw-type orders, as expected from the centrosymmetric crystal structure.
Article
Materials Science, Multidisciplinary
Aki Kitaori, Jonathan S. White, Naoya Kanazawa, Victor Ukleev, Deepak Singh, Yuki Furukawa, Taka-hisa Arima, Naoto Nagaosa, Yoshinori Tokura
Summary: AC current-driven motions of spiral spin textures can create new electric fields and induce emergent electromagnetic induction effect, potentially realizing quantum inductor elements of micrometer size. Research on YMn6Sn6 helimagnet reveals the optimized conditions for emergent inductors beyond room temperature, achieved by modifying the magnetism through partial substitution of Y by Tb. The study demonstrates the control of both magnitude and sign of emergent electromagnetic inductance, and expands the range of potential candidate materials for emergent inductors.
Article
Materials Science, Multidisciplinary
M. Kondo, M. Ochi, R. Kurihara, A. Miyake, Y. Yamasaki, M. Tokunaga, H. Nakao, K. Kuroki, T. Kida, M. Hagiwara, H. Murakawa, N. Hanasaki, H. Sakai
Summary: In this letter, we introduce a degenerate magnetic semiconductor EuMg2Bi2, which possesses topologically nontrivial Dirac/Weyl points formed by a magnetic exchange interaction with local Eu spins. Quantum oscillations in the resistivity, elastic constant, and surface impedance reveal the position of the Fermi energy EF and the existence of Weyl points near EF when the Eu spins are fully polarized, leading to an energy-dependent anomalous Hall conductivity peak. These findings are supported by first-principles calculations and demonstrate the significant impact of Weyl points on the simple band structure.
Article
Materials Science, Multidisciplinary
N. Matsuyama, T. Nomura, S. Imajo, T. Nomoto, R. Arita, K. Sudo, M. Kimata, N. D. Khanh, R. Takagi, Y. Tokura, S. Seki, K. Kindo, Y. Kohama
Summary: We have conducted magnetic torque and resistivity measurements on the centrosymmetric skyrmion host GdRu2Si2. Both de Haas-van Alphen and Shubnikov-de Haas oscillations were observed in the forced ferromagnetic phase. The angular dependence of the quantum oscillation frequencies can be explained by an ab initio calculation. The presence of a different de Haas-van Alphen oscillation frequency in the double-Q phase suggests a Fermi surface reconstruction due to coupling between localized spins and conduction electrons. Based on these experimental findings, the magnetic interactions in this system are discussed.
