Article
Materials Science, Multidisciplinary
A. V. Syromyatnikov
Summary: In this study, a spin-1/2 Heisenberg antiferromagnet on the triangular lattice was discussed using the bond-operator technique (BOT). It was found that high-energy collective excitations and another high-energy quasiparticle exist in the system. Quantum fluctuations considerably alter the properties of conventional magnons, and the anomalous spin dynamics observed experimentally recently cannot be described by SWT.
Article
Materials Science, Multidisciplinary
Benedikt Schneider, Jad C. Halimeh, Matthias Punk
Summary: This research provides a complete classification of fully symmetric and chiral Z(2) quantum spin liquids on the pyrochlore lattice using a projective symmetry group analysis of Schwinger boson mean-field states. The study identifies 50 independent Ansatze, including four chiral spin liquids that break the screw symmetry of the lattice. Additionally, the most general symmetry-allowed mean-field Hamiltonian for each class is specified.
Article
Materials Science, Multidisciplinary
Vera P. Bader, Jan Langmann, Philipp Gegenwart, Alexander A. Tsirlin
Summary: The crystal structure and thermodynamic properties of Na2SrCo(PO4)(2), a chemical sibling of the triangular quantum spin-liquid candidate Na2BaCo(PO4)(2), have been reported. The structural difference between the two compounds leads to changes in their magnetic properties.
Article
Materials Science, Multidisciplinary
Mutsuki Saito, Ryunosuke Takagishi, Nobuyuki Kurita, Masari Watanabe, Hidekazu Tanaka, Ryuji Nomura, Yoshiyuki Fukumoto, Kazuhiko Ikeuchi, Ryoichi Kajimoto
Summary: Cs2Cu3SnF12 and Rb2Cu3SnF12 are two spin-1/2 antiferromagnets with different structures, and their magnetic excitation structures were investigated using inelastic neutron scattering. Four single-magnon excitation modes were observed in Cs2Cu3SnF12, and a broad excitation continuum was found. In Rb2Cu3SnF12, singlet-triplet excitations from the pinwheel VBS state were confirmed, along with ghost modes caused by the enlargement of the chemical unit cell.
Article
Physics, Multidisciplinary
Leonardo Martinelli, Davide Betto, Kurt Kummer, Riccardo Arpaia, Lucio Braicovich, Daniele Di Castro, Nicholas B. Brookes, Marco Moretti Sala, Giacomo Ghiringhelli
Summary: Resonant inelastic x-ray scattering (RIXS) was used to investigate the magnetic dynamics of infinite-layer cuprate CaCuO2. It was found that the single magnon decays into a broad continuum of excitations, with the spin-flip character dominating. This continuum is proposed to originate from the decay of the magnon into spinon pairs, related to the high ring exchange J(c) of CaCuO2.
Article
Physics, Multidisciplinary
G. Zhang, Z. Song
Summary: We studied the impact of external fields on the energy level statistics and towers of eigenstates in spin-1/2 isotropic Heisenberg clusters. Different lattice structures were considered, including chain, ladder, square and triangular lattices. The presence of a uniform field in one direction allowed for a spectrum consisting mostly of towers with identical level spacing, thanks to the SU(2) symmetry. However, introducing random transverse fields in the other directions caused a transition from integrability to non-integrability, as evidenced by the change in level statistics from Poisson to Wigner-Dyson distributions. The largest tower still remained approximately intact even when the symmetry was broken, resulting in a quantum scar. Additionally, non-thermalized states, such as the Greenberger-Horn-Zeilinger and W states, were found to exhibit revival features while a Neel state decayed rapidly in dynamic processes. Several dynamic schemes for experimental detection were also proposed. Our findings suggest the potential for thermalization-immune quantum information processing in finite-sized spin clusters.
NEW JOURNAL OF PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Johannes Richter, Oleg Derzhko, Juergen Schnack
Summary: Over the last decade, the interest in the spin-1/2 Heisenberg antiferromagnet (HAF) on the square kagome lattice has been growing. This model system is a prominent example of quantum magnetism with a quantum paramagnetic ground state, flat-band physics near the saturation field, and quantum scars. Recent numerical investigations have revealed a gapless spin liquid in the square kagome magnet. The study also provides insights into specific heat, entropy, and susceptibility, revealing low-temperature shoulder below the major maximum and a change in curvature just at a specific temperature, attributed to low-lying singlet excitations and the singlet-triplet gap.
Article
Physics, Condensed Matter
Boqiang Li, Zongtang Wan, Yiru Song, Zhaohua Ma, Yuqian Zhao, Junfeng Wang, Yuesheng Li
Summary: We propose β-BaNi3(VO4)(2)(OH)(2) as a candidate for the spin-1 kagome Heisenberg antiferromagnet. Experimental measurements at low temperatures reveal properties similar to the pure S = 1 kagome Heisenberg antiferromagnetic model.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Materials Science, Multidisciplinary
Martin Ulaga, Jernej Mravlje, Jure Kokalj
Summary: The study reveals that spin diffusion in the Hubbard model exhibits a non-monotonic dependence on temperature, different from charge diffusion, due to the progressive liberation of charges contributing to spin transport. Moving away from half-filling and zero magnetization increases spin diffusion, but not enough to reconcile the differences between model calculations and recent measurements on cold atoms.
Article
Materials Science, Multidisciplinary
H. Yamaguchi, Y. Iwasaki, Y. Kono, T. Okubo, S. Miyamoto, Y. Hosokoshi, A. Matsuo, T. Sakakibara, T. Kida, M. Hagiwara
Summary: This study introduces a model compound with a spin-1/2 spatially anisotropic frustrated square lattice, showing an unconventional gradual increase in low-temperature magnetization curve and one-dimensional characteristics indicated by specific heat and electron spin resonance signals. These results demonstrate quantum critical behavior associated with one-dimensionalization caused by frustrated interactions in the spin-1/2 spatially anisotropic square lattice.
Article
Chemistry, Physical
Tyler J. Smart, Kejun Li, Junqing Xu, Yuan Ping
Summary: This study established a complete theoretical framework for accurately and systematically designing quantum defects in wide-bandgap 2D systems, focusing on essential static and dynamic properties for spin qubit discovery. Through thorough screening of defects based on first-principles calculations, promising single-photon emitters and spin qubits were identified in hexagonal boron nitride.
NPJ COMPUTATIONAL MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Sebin J. Sebastian, K. Somesh, M. Nandi, N. Ahmed, P. Bag, M. Baenitz, B. Koo, J. Sichelschmidt, A. A. Tsirlin, Y. Furukawa, R. Nath
Summary: The compound BaNa2Cu(VO4)(2) exhibits characteristics of a quasi-one-dimensional spin-1/2 Heisenberg chain model, with a centrosymmetric crystal structure. The experimental findings are consistent with theoretical estimations based on band-structure calculations, confirming the one-dimensional nature of the compound. Comparisons with a chemically similar but non-isostructural compound further support the unique properties of BaNa2Cu(VO4)(2).
Article
Physics, Multidisciplinary
Imre Hagymasi, Robin Schafer, Roderich Moessner, David J. Luitz
Summary: The study reveals a robust spontaneous inversion symmetry breaking in the S = 1/2 pyrochlore Heisenberg antiferromagnet, and suggests a scenario where a finite-temperature spin liquid regime transitions to a symmetry-broken state at low temperatures. The ground-state energy calculation and cluster size analysis provide insights into the properties of the quantum spin liquid candidate.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
T. A. Soldatov, A. I. Smirnov
Summary: A quasi-two-dimensional quantum magnet, BaCdVO(PO4)2, with competing ferro- and antiferromagnetic exchange interactions, was studied using magnetic resonance technique. The magnetic resonance spectra of the ordered phase showed a collinear antiferromagnetic spin structure along the a axis. The frequency-field diagram revealed two low-frequency excitation branches with different energy gaps, indicating a biaxial anisotropy nature. The softening of the longitudinal resonance mode at a field of 3.8 T was observed, suggesting the presence of a presaturation phase with variable magnetization of spin-vacancy defects.
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
Nanoscience & Nanotechnology
Hanshen Tsai, Tomoya Higo, Kouta Kondou, Ayuko Kobayashi, Takafumi Nakano, Kay Yakushiji, Shinji Miwa, Yoshichika Otani, Satoru Nakatsuji
Summary: The study demonstrates the SOT switching of the Hall resistance in Mn3Sn heterostructures, finding that the sign of the spin Hall angle of heavy metals determines the direction of magnetic switching and the critical current density is around 10(11)A/m(2). Additionally, it is discovered that the spin current generated from the spin Hall effect contributes dominantly to the SOT compared to possible interfacial effects.
Article
Materials Science, Multidisciplinary
Takafumi Nakano, Tomoya Higo, Ayuko Kobayashi, Shinji Miwa, Satoru Nakatsuji, Kay Yakushiji
Summary: The study found that high-quality Mn3Sn thin films can be fabricated using Pt and Cu seed materials, resulting in smooth and c-plane oriented structures after postannealing. Anomalous Nernst effect signals were not degraded by a small amount of Cu mixture, and the postannealing temperature could be effectively lowered.
PHYSICAL REVIEW MATERIALS
(2021)
Correction
Physics, Applied
Mio Ishibashi, Kay Yakushiji, Masashi Kawaguchi, Arata Tsukamoto, Satoru Nakatsuji, Masamitsu Hayashi
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Mio Ishibashi, Kay Yakushiji, Masashi Kawaguchi, Arata Tsukamoto, Satoru Nakatsuji, Masamitsu Hayashi
Summary: The magnetic properties of rare earth-transition metal ferrimagnetic thin films are studied. It is found that the compensation of magnetic moments of rare earth and transition metal sublattices increases with decreasing film thickness. For thin TbFeCo films, Tb atoms do not contribute to the magnetization. The perpendicular magnetic anisotropy increases with a thin Co layer but drops to zero with a thin Tb layer. The Tb concentration at which magnetic compensation occurs decreases when the underlayer is changed from Pt to Ta.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Takumi Matsuo, Tomoya Higo, Daisuke Nishio-Hamane, Satoru Nakatsuji
Summary: The magnetic Weyl semimetallic state in the chiral antiferromagnet Mn3Sn has attracted attention for its potential in memory technology. Despite having a very small magnetization, the material exhibits large transverse responses that can be electrically manipulated. Through experiments, it has been confirmed that thin polycrystalline Mn3Sn films with coarse surfaces have a discontinuous structure of grains with diameters of around 100 nm, and they retain the anomalous Hall effect at room temperature.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Zili Feng, Susumu Minami, Shuhei Akamatsu, Akito Sakai, Taishi Chen, Daisuke Nishio-Hamane, Satoru Nakatsuji
Summary: Recent discoveries of topological magnets have led to the development of a simpler thermoelectric conversion module through the use of the anomalous Nernst effect (ANE). Designing materials suitable for industrial processes is crucial for accelerating this innovation, thus there is a high demand for a high-ANE polycrystalline material. A giant and robust room-temperature ANE has been reported in single crystals of the topological ferromagnet Fe3Ga, which can potentially be used in a polycrystalline form for an ANE-based thermopile. The study also explores the effect of Fe doping on the transport properties of FexGa4-x, revealing that tuning the Fermi energy near the topological nodal-web structure is key to enhancing the ANE. A high value of more than 5.1 mu V K-1 is observed in an extended region of composition, confirming the robust characteristics of the topological electronic structure.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Physics, Multidisciplinary
M. Ikhlast, S. Dasgupta, F. Theuss, T. Higo, Shunichiro Kittaka, B. J. Ramshaw, O. Tchernyshyov, C. W. Hicks, S. Nakatsuji
Summary: Piezomagnetism is a linear coupling between strain and magnetic order, enabling the control of magnetization. This study reports the observation of large piezomagnetism at room temperature in an antiferromagnetic Weyl semimetal, which allows strain to control the anomalous Hall effect. This finding has the potential for spintronics applications.
Article
Physics, Applied
Mio Ishibashi, Kay Yakushiji, Masashi Kawaguchi, Arata Tsukamoto, Satoru Nakatsuji, Masamitsu Hayashi
Summary: We conducted a systematic study on the current-induced motion of domain walls in TbFeCo ferrimagnetic thin films with a Pt underlayer. By varying the Tb concentration, we investigated the effect of magnetization compensation on the domain wall motion. We observed that the direction of domain wall movement changes at the magnetization compensation point, with FeCo-rich films moving against the current flow. When the film composition is slightly Tb-rich, the domain wall initially moves along the current but reverses its direction with increased current. These findings suggest the presence of competing torques in Tb-based ferrimagnets, resulting in slower domain wall velocity compared to Gd-based ferrimagnets.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Review
Materials Science, Multidisciplinary
Tomoya Higo, Satoru Nakatsuji
Summary: This article reviews the recent research progress on Mn3Sn, highlighting its functional properties as a metallic non-collinear antiferromagnet, and focusing on the fabrication and properties of Mn3Sn thin films essential for device applications.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Hirokazu Tanaka, Tomoya Higo, Ryota Uesugi, Kazuto Yamagata, Yosuke Nakanishi, Hironobu Machinaga, Satoru Nakatsuji
Summary: The anomalous Nernst effect allows the conversion of perpendicular heat flux into electricity, facilitating large-scale production and flexibility through common thin-film techniques. ANE-based heat flux sensors can effectively evaluate heat flow and contribute to energy savings. However, the presence of in-plane heat flux complicates the evaluation of perpendicular heat flux. This study fabricates ANE-type heat flux sensors with selective detection of perpendicular heat flux, enabling practical application of thin-film thermoelectric devices through a simple fabrication process.
ADVANCED MATERIALS
(2023)
Article
Physics, Applied
Nico Budai, Hironari Isshiki, Ryota Uesugi, Zheng Zhu, Tomoya Higo, Satoru Nakatsuji, YoshiChika Otani
Summary: We propose a magnetic imaging technique using atomic force microscopy to measure the locally induced anomalous Nernst effect. By creating a local temperature gradient on a sample surface through tip contact and a neighboring Joule heating wire, we are able to image magnetic domains in the ferromagnetic Weyl semimetal Co2MnGa at room temperature with sub-hundred nanometer spatial resolution.
APPLIED PHYSICS LETTERS
(2023)
Article
Multidisciplinary Sciences
Hisao Kobayashi, Yui Sakaguchi, Hayato Kitagawa, Momoko Oura, Shugo Ikeda, Kentaro Kuga, Shintaro Suzuki, Satoru Nakatsuji, Ryo Masuda, Yasuhiro Kobayashi, Makoto Seto, Yoshitaka Yoda, Kenji Tamasaku, Yashar Komijani, Premala Chandra, Piers Coleman
Summary: Using synchrotron radiation-based Mossbauer spectroscopy, we investigated the charge fluctuations of beta-YbAlB4's strange metal phase and observed the splitting of the absorption peak in the Fermi-liquid regime upon entering the critical regime. This splitting is interpreted as a result of single nuclear transition modulated by nearby electronic valence fluctuations, which are further enhanced by the formation of charged polarons. These critical charge fluctuations may serve as a distinctive signature of strange metals.
Article
Chemistry, Multidisciplinary
Hirokazu Tanaka, Tomoya Higo, Ryota Uesugi, Kazuto Yamagata, Yosuke Nakanishi, Hironobu Machinaga, Satoru Nakatsuji
Summary: ANE-type heat flux sensors, fabricated using mass-producible roll-to-roll sputtering methods, selectively detect perpendicular heat flux by adjusting the net Seebeck coefficient in their thermopile circuit, paving the way for practical applications of thin-film thermoelectric devices.
ADVANCED MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Florian Theuss, Sayak Ghosh, Taishi Chen, Oleg Tchernyshyov, Satoru Nakatsuji, B. J. Ramshaw
Summary: In this study, we measure the full elastic tensors of Mn3Ge and Mn3Sn as a function of temperature and find strong magnetoelastic coupling in their respective antiferromagnetic phase transitions. The discontinuities in bulk moduli at the N??el transitions are significantly larger in Mn3Ge than in Mn3Sn, and we calculate the pressure derivatives of the N??el temperature based on the magnitudes of the discontinuities. Additionally, we measure the in-plane shear modulus in both compounds under different magnetic fields and observe similar behavior. Recent experiments have shown strong piezomagnetism in Mn3Sn, and our results suggest that Mn3Ge may be an even better candidate for this effect.
Article
Materials Science, Multidisciplinary
Shoya Sakamoto, Tomoya Higo, Masanobu Shiga, Kenta Amemiya, Satoru Nakatsuji, Shinji Miwa
Summary: In this paper, spontaneous XMCD spectra originating from the inverse triangular spin structure or the polarization of the cluster magnetic octupole were observed in the chiral antiferromagnet Mn3Sn thin film, which is consistent with recent theoretical predictions. This suggests that the inverse triangular spin structure can give rise to finite XMCD signals in the absence of net magnetization.
