Article
Multidisciplinary Sciences
Krzysztof Gawryluk, Miroslaw Brewczyk
Summary: In this study, the sound propagation in a two-dimensional weakly interacting uniform Bose gas is theoretically explored using classical fields approximation. Density waves generated in both weak and strong perturbation regimes are analyzed, with strong disturbances resulting in a qualitatively different response, identified as quasisolitons. In the strong perturbation regime, quasisolitons break into vortex pairs over time, eventually reaching an equilibrium state characterized by fluctuating in time averaged number of pairs of opposite charge vortices and quasi-long-range order, known as the Berezinskii-Kosterlitz-Thouless (BKT) phase.
SCIENTIFIC REPORTS
(2021)
Article
Physics, Multidisciplinary
Guido Giachetti, Nicolo Defenu, Stefano Ruffo, Andrea Trombettoni
Summary: The article discusses the effect of long-range decaying couplings on the BKT transition, revealing a phase diagram far richer than the short-range scenario, with a quasiordered phase existing between a symmetry broken phase and a disordered phase.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Fluids & Plasmas
Kwai-Kong Ng, Ching-Yu Huang, Feng-Li Lin
Summary: The Berezinskii-Kosterlitz-Thouless (BKT) phase transitions of the two-dimensional q-state clock model with q=4 is studied using the neural network (NN) flow method. The Jensen-Shannon divergence (JSD) is adopted as the information-distance measure thermometer to gauge the difference among Monte Carlo configurations at different temperatures, and to identify the critical temperatures of BKT phase transitions. The results show that the NN flow can flow an arbitrary spin state to a fixed-point ensemble of states, and the JSD of the fixed-point ensemble exhibits unique features.
Article
Physics, Multidisciplinary
D. Opherden, M. S. J. Tepaske, F. Baertl, M. Weber, M. M. Turnbull, T. Lancaster, S. J. Blundell, M. Baenitz, J. Wosnitza, C. P. Landee, R. Moessner, D. J. Luitz, H. Kuehne
Summary: We report the manifestation of field-induced Berezinskii-Kosterlitz-Thouless (BKT) correlations in the weakly coupled spin-1/2 Heisenberg layers of the molecular-based bulk material. The application of laboratory magnetic fields induces a substantial XY anisotropy of the spin correlations, providing a significant BKT regime. We use nuclear magnetic resonance measurements and quantum Monte Carlo simulations to probe and study the spin correlations.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Domenico Giuliano, Phong H. Nguyen, Andrea Nava, Massimo Boninsegni
Summary: We present a theoretical study on the Berezinskii-Kosterlitz-Thouless transition in a two-dimensional superfluid with an externally imposed density modulation. Using analytical and numerical techniques, we show that as the modulation amplitude increases, the system exhibits behavior similar to the anisotropic x-y model, with a lower superfluid transition temperature and anisotropic response, but no dimensional crossover.
Article
Physics, Multidisciplinary
G. Dagvadorj, P. Comaron, M. H. Szyma
Summary: We investigate a four-component polariton system in the optical parametric oscillator regime and find that all four components exhibit the same BKT critical point and algebraic decay of spatial coherence. However, the creation of topological defects near the phase transition is largely independent of intercomponent mode locking and strongly depends on the density within a given mode. This unique characteristic allows us to discover a novel state of matter characterized by the proliferation of topological defects on a superfluid with algebraic decay of coherence, which can be observed in current experiments.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
B. Flebus
Summary: The study investigates the interplay between electronic and magnetic degrees of freedom near the BKT transition. By focusing on a metal with easy-plane ferromagnetic order, a framework is established that accounts for the coupling between charge current and the flow of topological magnetic defects, leading to the discovery of a temperature-dependent magnetoresistance effect scaling with the density of topological defects.
Letter
Chemistry, Multidisciplinary
Arthur Veyrat, Valentin Labracherie, Dima L. Bashlakov, Federico Caglieris, Jorge I. Facio, Grigory Shipunov, Titouan Charvin, Rohith Acharya, Yurii Naidyuk, Romain Giraud, Jeroen van den Brink, Bernd Buechner, Christian Hess, Saicharan Aswartham, Joseph Dufouleur
Summary: In this study, it is predicted that broken inversion symmetry and strong spin-orbit coupling in trigonal PtBi2 lead to a type-I Weyl semimetal band structure. Transport measurements reveal unusually robust low dimensional superconductivity in thin exfoliated flakes of PtBi2, with thickness up to 126 nm and critical temperature (T-c) ranging from 275-400 mK. A Berezinskii-Kosterlitz-Thouless transition with critical temperature (T-BKT) around 310 mK is observed in up to 60 nm thick flakes, which is significantly thicker than rare examples of two-dimensional superconductors exhibiting such a transition. PtBi2 thus provides an ideal platform to study low dimensional and unconventional superconductivity in topological semimetals.
Article
Materials Science, Multidisciplinary
Fernando Gomez-Ortiz, Pablo Garcia-Fernandez, Juan M. Lopez, Javier Junquera
Summary: We investigated the emergence of Berezinskii-Kosterlitz-Thouless (BKT) phases in (PbTiO3)3/(SrTiO3)3 superlattices using second-principles simulations. Under a tensile epitaxial strain of e = 0.25-1%, the local dipole moments within the superlattices are confined to the film-plane, leading to two-dimensional polarization. Our analysis of dipole-dipole correlation decay, density of defects, and temperature dependence supports the existence of a BKT phase, characterized by quasi-long-range order and the presence of tightly bound vortex-antivortex pairs. This proposed superlattice model can be experimentally verified due to its feasibility in fabrication and the imposed mechanical boundary conditions.
Article
Physics, Multidisciplinary
Alexander Weitzel, Lea Pfaffinger, Ilaria Maccari, Klaus Kronfeldner, Thomas Huber, Lorenz Fuchs, James Mallord, Sven Linzen, Evgeni Il'Ichev, Nicola Paradiso, Christoph Strunk
Summary: We conducted a comprehensive investigation of the Berezinskii-Kosterlitz-Thouless transition in ultrathin strongly disordered NbN films. Our measurements of resistance, current-voltage characteristics, and kinetic inductance on the same device provide consistent evidence for a sharp unbinding transition of vortex-antivortex pairs, which can be explained by standard renormalization group theory without extra assumptions of inhomogeneity. Our experiments demonstrate that the previously observed broadening of the transition is not intrinsic to strongly disordered superconductors, and provide a clean starting point for studying dynamical effects at the Berezinskii-Kosterlitz-Thouless transition.
PHYSICAL REVIEW LETTERS
(2023)
Article
Optics
Koichiro Furutani, Andrea Perali, Luca Salasnich
Summary: We theoretically investigate the Berezinskii-Kosterlitz-Thouless transition in a binary mixture of bosonic atoms with Rabi coupling. The transition temperature shows a nonmonotonic behavior with respect to the intercomponent coupling and an amplification for finite Rabi coupling. By developing the Nelson-Kosterlitz renormalization-group equations, we clarify the dependence of the transition temperature on the Rabi coupling and the intercomponent coupling. Our results contribute to the understanding of multicomponent quantum systems, such as multiband superconductors.
Article
Materials Science, Multidisciplinary
Y-H Tseng, F-J Jiang
Summary: By using a supervised neural network trained on a one-dimensional lattice, the study successfully calculated the Berezinskii-Kosterlitz-Thouless phase transitions of two-dimensional classical XY models. The neural network approach proved to be accurate in predicting critical points with minimal information and demonstrated efficiency in computation. This universal neural network is not only valid for symmetry breaking related phase transitions, but also for calculating critical points associated with topology.
RESULTS IN PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Kevin T. Grosvenor, Ruben Lier, Piotr Surowka
Summary: In this study, the nature of BKT transitions in the three-dimensional plaquette-dimer model is determined using modified dimensional analysis. The beta functions of the model are computed, and a finite critical value is predicted above which the fractonic phase melts, leading to the proliferation of dipoles. Importantly, the renormalization group analysis takes into account the UV/IR mixing characteristic of fractonic models.
Article
Materials Science, Multidisciplinary
Guido Giachetti, Andrea Trombettoni, Stefano Ruffo, Nicolo Defenu
Summary: In this paper, a field-theoretical treatment of the 2D XY model with long-range couplings is discussed, and it is compared with results from the self-consistent harmonic approximation. The results show that both power law BKT scaling and spontaneous symmetry breaking occur for the same decay rates of long-range interactions. Meanwhile, the Villain approximation fails to reproduce the correct critical behavior in the long-range regime.
Article
Physics, Multidisciplinary
Feng Xu, Lei Zhang, Liyun Jiang, Chung-Yu Mou
Summary: The study demonstrates that flat-band superconductivity in strained graphene can significantly increase the superconducting transition temperature, while the superfluid weight of pure superconducting pair-density-wave states exhibits a transition temperature much lower than the pair density wave gap-opening temperature.
CHINESE JOURNAL OF PHYSICS
(2021)
