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Marcenat C, Klein T, LeBoeuf D, Jaoui A, Seyfarth G, Kačmarčík J, Kohama Y, Cercellier H, Aubin H, Behnia K, Fauqué B. Wide Critical Fluctuations of the Field-Induced Phase Transition in Graphite. Phys Rev Lett 2021; 126:106801. [PMID: 33784120 DOI: 10.1103/physrevlett.126.106801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/28/2021] [Indexed: 06/12/2023]
Abstract
In the immediate vicinity of the critical temperature (T_{c}) of a phase transition, there are fluctuations of the order parameter that reside beyond the mean-field approximation. Such critical fluctuations usually occur in a very narrow temperature window in contrast to Gaussian fluctuations. Here, we report on a study of specific heat in graphite subject to a high magnetic field when all carriers are confined in the lowest Landau levels. The observation of a BCS-like specific heat jump in both temperature and field sweeps establishes that the phase transition discovered decades ago in graphite is of the second order. The jump is preceded by a steady field-induced enhancement of the electronic specific heat. A modest (20%) reduction in the amplitude of the magnetic field (from 33 to 27 T) leads to a threefold decrease of T_{c} and a drastic widening of the specific heat anomaly, which acquires a tail spreading to two times T_{c}. We argue that the steady departure from the mean-field BCS behavior is the consequence of an exceptionally large Ginzburg number in this dilute metal, which grows steadily as the field lowers. Our fit of the critical fluctuations indicates that they belong to the 3DXY universality class as in the case of the ^{4}He superfluid transition.
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Affiliation(s)
- Christophe Marcenat
- Université Grenoble Alpes, CEA, IRIG, PHELIQS, LATEQS, F-38000 Grenoble, France
| | - Thierry Klein
- Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, F-38000 Grenoble, France
| | - David LeBoeuf
- Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), CNRS, UGA, UPS, INSA, 38042 Grenoble/Toulouse, France
| | - Alexandre Jaoui
- JEIP, USR 3573 CNRS, Collège de France, PSL Research University, 11, Place Marcelin Berthelot, 75231 Paris Cedex 05, France
- Laboratoire de Physique et Etude des Matériaux (CNRS/UPMC), Ecole Supérieure de Physique et de Chimie Industrielles, 10 Rue Vauquelin, 75005 Paris, France
| | - Gabriel Seyfarth
- Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), CNRS, UGA, UPS, INSA, 38042 Grenoble/Toulouse, France
| | - Jozef Kačmarčík
- Centre of Low Temperature Physics, Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, SK-04001 Košice, Slovakia
| | - Yoshimitsu Kohama
- The Institute of Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Hervé Cercellier
- Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, F-38000 Grenoble, France
| | - Hervé Aubin
- Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Saclay, 91120 Palaiseau, France
| | - Kamran Behnia
- Laboratoire de Physique et Etude des Matériaux (CNRS/UPMC), Ecole Supérieure de Physique et de Chimie Industrielles, 10 Rue Vauquelin, 75005 Paris, France
| | - Benoît Fauqué
- JEIP, USR 3573 CNRS, Collège de France, PSL Research University, 11, Place Marcelin Berthelot, 75231 Paris Cedex 05, France
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Monney C, Zhou KJ, Cercellier H, Vydrova Z, Garnier MG, Monney G, Strocov VN, Berger H, Beck H, Schmitt T, Aebi P. Mapping of electron-hole excitations in the charge-density-wave system 1T-TiSe2 using resonant inelastic x-ray scattering. Phys Rev Lett 2012; 109:047401. [PMID: 23006106 DOI: 10.1103/physrevlett.109.047401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Indexed: 06/01/2023]
Abstract
In high-resolution resonant inelastic x-ray scattering at the Ti L edge of the charge-density-wave system 1T-TiSe(2), we observe sharp low energy loss peaks from electron-hole pair excitations developing at low temperature. These excitations are strongly dispersing as a function of the transferred momentum of light. We show that the unoccupied bands close to the Fermi level can effectively be probed in this broadband material. Furthermore, we extract the order parameter of the charge-density-wave phase from temperature-dependent measurements.
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Affiliation(s)
- C Monney
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
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Monney C, Battaglia C, Cercellier H, Aebi P, Beck H. Exciton condensation driving the periodic lattice distortion of 1T-TiSe2. Phys Rev Lett 2011; 106:106404. [PMID: 21469817 DOI: 10.1103/physrevlett.106.106404] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Indexed: 05/30/2023]
Abstract
We address the lattice deformation of 1T-TiSe2 within the exciton condensate phase. We show that, at low temperature, condensed excitons influence the lattice through electron-phonon interaction. It is found that at zero temperature, in the exciton condensate phase of 1T-TiSe2, this exciton condensate exerts a force on the lattice generating ionic displacements comparable in amplitude to what is measured in experiment. This is thus the first quantitative estimation of the amplitude of the periodic lattice distortion observed in 1T-TiSe2 as a consequence of the exciton condensate phase.
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Affiliation(s)
- C Monney
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, CH-1700 Fribourg, Switzerland
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Klein T, Marlaud R, Marcenat C, Cercellier H, Konczykowski M, van der Beek CJ, Mosser V, Lee HS, Lee SI. First-order transition in the magnetic vortex matter in superconducting MgB2 tuned by disorder. Phys Rev Lett 2010; 105:047001. [PMID: 20867876 DOI: 10.1103/physrevlett.105.047001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Indexed: 05/29/2023]
Abstract
The field-driven transition from an ordered Bragg glass to a disordered vortex phase in single-crystalline MgB2 is tuned by an increasing density of point defects, introduced by electron irradiation. The discontinuity observed in magnetization attests to the first-order nature of the transition. The temperature and defect density dependences of the transition field point to vortex pinning mediated by fluctuations in the quasiparticle mean free path, and reveal the mechanism of the transition in the absence of complicating factors such as layeredness or thermal fluctuations.
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Affiliation(s)
- T Klein
- Institut Néel, CNRS, 25 rue des martyrs, 38042 Grenoble, France
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Cercellier H, Monney C, Clerc F, Battaglia C, Despont L, Garnier MG, Beck H, Aebi P, Patthey L, Berger H, Forró L. Evidence for an excitonic insulator phase in 1T-TiSe2. Phys Rev Lett 2007; 99:146403. [PMID: 17930692 DOI: 10.1103/physrevlett.99.146403] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Indexed: 05/25/2023]
Abstract
We present a new high-resolution angle-resolved photoemission study of 1T-TiSe2 in both its room-temperature, normal phase and its low-temperature, charge-density wave phase. At low temperature the photoemission spectra are strongly modified, with large band renormalizations at high-symmetry points of the Brillouin zone and a very large transfer of spectral weight to backfolded bands. A calculation of the theoretical spectral function for an excitonic insulator phase reproduces the experimental features with very good agreement. This gives strong evidence in favor of the excitonic insulator scenario as a driving force for the charge-density wave transition in 1T-TiSe2.
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Affiliation(s)
- H Cercellier
- Institut de Physique, Université de Neuchâtel, CH-2000, Neuchâtel, Switzerland.
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