Article
Physics, Multidisciplinary
K. Gotze, M. J. Pearce, M. J. Coak, P. A. Goddard, A. D. Grockowiak, W. A. Coniglio, S. W. Tozer, D. E. Graf, M. B. Maple, P-C Ho, M. C. Brown, J. Singleton
Summary: CeOs4Sb12, a member of the skutterudite family, exhibits an unusual semimetallic low-temperature L-phase. The influence of pressure on the different H-T phase boundaries in CeOs4Sb12 was investigated through electrical transport and megahertz conductivity measurements. The results showed changes in properties such as the decrease in Fermi surface size and marginal suppression of the low-temperature phase under high pressure.
NEW JOURNAL OF PHYSICS
(2022)
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
Multidisciplinary Sciences
S. Rahul, Nilanjan Roy, Ranjith R. R. Kumar, Y. R. Kartik, Sujit Sarkar
Summary: We investigate the nature of quantum criticality and topological phase transitions in the extended Kitaev chain with next nearest neighbor hopping parameters and non-Hermitian chemical potential. Multiple gap-less points are found, whose locations in momentum space can change along the critical line unlike the Hermitian counterpart. Interesting simultaneous occurrences of vanishing and sign flipping behavior by real and imaginary components, respectively of the lowest excitation are observed near the topological phase transition. Introduction of non-Hermitian factor leads to an isolated critical point instead of a critical line and reduced number of multi-critical points compared to the Hermitian case. The critical exponents obtained for the multi-critical and critical points show a very distinct behavior from the Hermitian case.
SCIENTIFIC REPORTS
(2023)
Article
Physics, Condensed Matter
Shinji Watanabe
Summary: The elastic properties of the quantum critical quasicrystal Yb15Al34Au51 were analyzed based on the approximant crystal Yb14Al35Au51. Softening of elastic constants was observed in the bulk modulus and longitudinal mode at low temperatures, likely due to the quantum critical point near the Yb-valence transition. The results suggest possible relevance to the quasicrystal and pressure-tuned approximant crystal.
SOLID STATE COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Mikhail A. Belyanchikov, Maxim Savinov, Petr Proschek, Jan Prokleska, Elena S. Zhukova, Victor G. Thomas, Zakhar V. Bedran, Filip Kadlec, Stanislav Kamba, Martin Dressel, Boris P. Gorshunov
Summary: In this study, the radio frequency dielectric response of a system composed of water molecules arranged in nanocages was investigated. Quantum effects were found to dominate the properties of the electric dipolar system at low temperatures. By comparing with conventional quantum paraelectrics, clear signatures of quantum-critical behavior were observed.
Review
Physics, Multidisciplinary
Michael Smidman, Oliver Stockert, Emilian M. Nica, Yang Liu, Huiqiu Yuan, Qimiao Si, Frank Steglich
Summary: This Colloquium surveys apparently conflicting results from multiple experimental studies on the heavy-fermion metal CeCu2Si2. Different theoretical scenarios, including isotropic and anisotropic two-band s-wave superconductivity, as well as an effective two-band d-wave model, are addressed to understand the particular gap structure. Lessons learned from CeCu2Si2 are expected to contribute to uncovering Cooper-pair states in other unconventional, fully gapped superconductors with strongly correlated carriers.
REVIEWS OF MODERN PHYSICS
(2023)
Article
Physics, Multidisciplinary
Weicheng Ye, Sung-Sik Lee, Liujun Zou
Summary: The study reveals that through UV-IR mixing, higher-loop processes can enhance coupling at low energies, shrinking the basin of attraction for the weakly coupled fixed point of a (2+1)dimensional MFL to a measure-zero set in the low-energy limit. This effect is caused by gapless virtual Cooper pairs that spread over the entire FS through marginal long-range interactions, signaling a breakdown of the patch description for the MFL and questioning the validity of using the MFL as the base theory in a controlled scheme for non-Fermi liquids arising from relevant long-range interactions.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Giulia Piccitto, Michele Campisi, Davide Rossini
Summary: We study a four-stroke Otto engine with a quantum Ising chain as the working fluid. The thermodynamic cycle consists of sweeps of the transverse magnetic field and thermalisation strokes with reservoirs at different temperatures. The system-environment coupling is modelled using a nonlocal Lindblad master equation. We find that the engine can operate in four different modes and exhibit enhanced thermodynamic performance near the critical point.
NEW JOURNAL OF PHYSICS
(2022)
Article
Multidisciplinary Sciences
Wataru Higemoto, Makoto Yokoyama, Takashi U. Ito, Taiga Suzuki, Stephane Raymond, Youichi Yanase
Summary: Experimental results in the compound CeCo(In1-xZnx)5 show that the magnitude of the magnetic moment decreases and eventually vanishes with decreasing impurity concentration in the coexistence region of superconductivity and magnetic ordering, indicating the presence of a second-order phase transition and a quantum critical point.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Chemistry, Multidisciplinary
Ngoc-Toan Dang, Denis P. Kozlenko, Olga N. Lis, Sergey E. Kichanov, Yevgenii V. Lukin, Natalia O. Golosova, Boris N. Savenko, Dinh-Loc Duong, The-Long Phan, Tuan-Anh Tran, Manh-Huong Phan
Summary: The effects of pressure (0-20 GPa) on the magnetic and structural properties of Fe3GeTe2 are investigated. It is found that ferromagnetic ordering is suppressed and a paramagnetic ground state emerges under pressure exceeding a critical value of P-PM ~ 15 GPa. An anomalous pressure dependence of structural parameters and vibrational modes is observed at P-C ~ 7 GPa, which is attributed to an isostructural phase transformation. Density functional theory calculations support these experimental findings. This study highlights the importance of pressure in driving magnetic quantum criticality in layered vdW magnetic systems.
Article
Physics, Multidisciplinary
Srikanth Sastry
Summary: Investigations indicate a strong dependence of yielding behavior of amorphous solids on the degree of annealing, with a qualitative change in the nature of yielding above a threshold annealing degree. Theoretical studies have mainly focused on uniform deformation in amorphous solids, while intriguing features of cyclic deformation remain unexplored. The study on athermal cyclic deformation introduces models that reproduce key features observed in simulations and provide an interpretation for the presence of a threshold energy.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Valentin Crepel, Tommaso Cea, Liang Fu, Francisco Guinea
Summary: In this study, we analyze the superconductivity in a multiband system with repulsive interactions using an extended Hubbard model. We find that virtual interband processes lead to an effective attractive interaction for small momentum transfers, which is different from most models of superconductivity from repulsion. This attractive interaction can be attributed to the presence of correlated hopping terms induced by interband polarization in real space. Our analysis employs strong-coupling expansion, many-body perturbation theory, and numerical calculations. We also draw interesting parallels between our findings and the problem of interacting electrons in twisted bilayer graphene, highlighting the importance of the interband contribution to superconductivity.
Article
Physics, Multidisciplinary
Bjorn Sbierski, Elizabeth J. Dresselhaus, Joel E. Moore, Ilya A. Gruzberg
Summary: The study presents extensive numerical results on the phase diagram and criticality of 2D DDF in the unitary class, revealing a critical line at m = 0 with an energy-dependent localization length exponent. The results challenge conjectured relations between different IQHT models.
PHYSICAL REVIEW LETTERS
(2021)
Article
Mechanics
Yoshihiro Nishiyama
Summary: The two-dimensional spin-S = 1XY model was numerically investigated as a realization of the (2 vertical bar 1)D superfluid-Mott-insulator transition. By applying an external field of a unit flux quantum, the excess energy cost in the superfluid phase was evaluated, revealing a notable plateau near the critical point.
JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT
(2022)
Article
Materials Science, Multidisciplinary
Zhentao Wang, Dominique Gautreau, Turan Birol, Rafael M. Fernandes
Summary: Rare-earth titanates are Mott insulators whose magnetic ground state can be tuned between antiferromagnetic and ferromagnetic states by substituting rare-earth elements. This study combines phenomenology and first-principles calculations to analyze the magnetic phase diagram and reveals the presence of a first-order metamagnetic transition line and a Widom line that can be tuned to zero temperature using strain.
Article
Physics, Multidisciplinary
Shinji Watanabe, Kazumasa Miyake
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2019)
Article
Physics, Condensed Matter
Shinji Watanabe, Kazumasa Miyake
SOLID STATE COMMUNICATIONS
(2020)
Article
Physics, Multidisciplinary
Shinji Watanabe
Summary: Recent discoveries of a new type of quantum criticality arising from Yb-valence fluctuations in Yb-based metal in periodic crystal and quasicrystal have opened a new class of quantum critical phenomena in correlated electron systems. By studying SmS, it is shown that the Coulomb repulsion between 4f and 5d orbitals at Sm drives first-order valence transition (FOVT) and semimetal-to-insulator transition (MIT) simultaneously, explaining the golden-black phase transition. The ground-state phase diagram for the FOVT and MIT is clarified by identifying the quantum critical point of the FOVT, with exciton condensates found in both semimetal and insulator phases.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2021)
Article
Physics, Multidisciplinary
Shinji Watanabe, Mina Kawamoto
Summary: The study investigates the crystalline electronic field of rare-earth based crystals using the point charge model and operator equivalent method, finding that the valence ratio of ligand ions plays a crucial role in characterizing the ground state of the crystalline electronic field. This formulation is generally applicable to rare-earth-based quasicrystals and approximant crystals, providing insights into the quantum properties of ligand ions.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2021)
Article
Multidisciplinary Sciences
Shinji Watanabe
Summary: In quasicrystals, the crystalline electric field of rare-earth elements plays a key role in the unique magnetic textures and topological states, which can be manipulated by controlling the compositions of non-rare-earth elements in the compounds.
SCIENTIFIC REPORTS
(2021)
Article
Multidisciplinary Sciences
Shinji Watanabe
Summary: The study reveals the presence of ferromagnetic long-range order in Tb-based quasicrystals, characterized by unique magnetic textures driven by magnetic anisotropy, leading to various magnetic states and topological structures. Under applied magnetic field, these states exhibit the topological Hall effect and topological metamagnetic transition.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Physics, Condensed Matter
Shinji Watanabe
Summary: The elastic properties of the quantum critical quasicrystal Yb15Al34Au51 were analyzed based on the approximant crystal Yb14Al35Au51. Softening of elastic constants was observed in the bulk modulus and longitudinal mode at low temperatures, likely due to the quantum critical point near the Yb-valence transition. The results suggest possible relevance to the quasicrystal and pressure-tuned approximant crystal.
SOLID STATE COMMUNICATIONS
(2021)
Article
Multidisciplinary Sciences
Shinji Watanabe
Summary: Quasicrystals have unique lattice structures and rotational symmetries that differ from periodic crystals. The electric state and physical property of quasicrystals are not yet fully understood. Recent discovery of ferromagnetic long-range order in rare-earth-based quasicrystals has provided new insights into their magnetic dynamics.
SCIENTIFIC REPORTS
(2022)
Article
Materials Science, Multidisciplinary
Tetsu Watanuki, Masaichiro Mizumaki, Shinji Watanabe, Naomi Kawamura, Kiyofumi Nitta, Akihiko Machida, Tsutomu Ishimasa
Summary: In this paper, the temperature dependence of Yb valence in an Au-Al-Yb intermediate-valence quasicrystal is investigated. The results show that the Yb valence increases as the temperature decreases, consistent with the anomalous suppression of thermal shrinkage reported previously. The effect of the Yb valence changes on the volume is also quantitatively analyzed.
MATERIALS TRANSACTIONS
(2022)
Article
Multidisciplinary Sciences
Shinji Watanabe
Summary: Quasicrystals possess a unique lattice structure without translational invariance, and recent research has revealed the structure and dynamics of the ferromagnetic hedgehog state in the icosahedral quasicrystal. The study shows that the magnetic excitation mode exhibits streak fine structure in the q-energy plane, characteristic of the hedgehog state in the icosahedral quasicrystal.
SCIENTIFIC REPORTS
(2022)
Proceedings Paper
Crystallography
Shinji Watanabe
Summary: Quasicrystals have unique rotational symmetry and lack periodicity. Understanding their electric and magnetic properties has been hindered by the lack of a microscopic theory of the crystalline electric field (CEF). However, by developing a general formulation of the CEF in rare-earth based quasicrystals, we have been able to analyze their CEF and magnetic anisotropy. This has allowed us to study the ground-state properties and unique magnetic states in quasicrystals and their approximant crystals.
10TH INTERNATIONAL CONFERENCE ON APERIODIC CRYSTALS, APERIODIC 2022
(2023)
Article
Materials Science, Multidisciplinary
S. E. Dissanayake, F. Ye, W. Tian, M. Matsuda, H. Muto, S. Suzuki, T. Nakano, S. Watanabe, J. Gouchi, Y. Uwatoko
Summary: CePtSi2 exhibits antiferromagnetic order at ambient pressure and superconductivity under high pressure, with a possible intermediate phase between the two. Magnetic fluctuations may play a primary role in the superconducting pairing mechanism.
Article
Materials Science, Multidisciplinary
Shinji Watanabe, Kazumasa Miyake
Article
Materials Science, Multidisciplinary
Kazumasa Miyake, Shinji Watanabe
Article
Materials Science, Multidisciplinary
Gernot W. Scheerer, Zhi Ren, Shinji Watanabe, Gerard Lapertot, Dai Aoki, Didier Jaccard, Kazumasa Miyake
NPJ QUANTUM MATERIALS
(2018)