1
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Tokunaga Y, Sakai H, Kambe S, Opletal P, Tokiwa Y, Haga Y, Kitagawa S, Ishida K, Aoki D, Knebel G, Lapertot G, Krämer S, Horvatić M. Longitudinal Spin Fluctuations Driving Field-Reinforced Superconductivity in UTe_{2}. PHYSICAL REVIEW LETTERS 2023; 131:226503. [PMID: 38101342 DOI: 10.1103/physrevlett.131.226503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 09/29/2023] [Accepted: 10/18/2023] [Indexed: 12/17/2023]
Abstract
Our measurements of ^{125}Te NMR relaxations reveal an enhancement of electronic spin fluctuations above μ_{0}H^{*}∼15 T, leading to their divergence in the vicinity of the metamagnetic transition at μ_{0}H_{m}≈35 T, below which field-reinforced superconductivity appears when a magnetic field (H) is applied along the crystallographic b axis. The NMR data evidence that these fluctuations are dominantly longitudinal, providing a key to understanding the peculiar superconducting phase diagram in H∥b, where such fluctuations enhance the pairing interactions.
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Affiliation(s)
- Y Tokunaga
- ASRC, Japan Atomic Energy Agency Tokai, Ibaraki 319-1195, Japan
| | - H Sakai
- ASRC, Japan Atomic Energy Agency Tokai, Ibaraki 319-1195, Japan
| | - S Kambe
- ASRC, Japan Atomic Energy Agency Tokai, Ibaraki 319-1195, Japan
| | - P Opletal
- ASRC, Japan Atomic Energy Agency Tokai, Ibaraki 319-1195, Japan
| | - Y Tokiwa
- ASRC, Japan Atomic Energy Agency Tokai, Ibaraki 319-1195, Japan
| | - Y Haga
- ASRC, Japan Atomic Energy Agency Tokai, Ibaraki 319-1195, Japan
| | - S Kitagawa
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - K Ishida
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - D Aoki
- IMR, Tohoku University, Ibaraki 311-1313, Japan
- Université Grenoble Alpes, CEA, Grenoble-INP, IRIG, Pheliqs, 38000 Grenoble, France
| | - G Knebel
- Université Grenoble Alpes, CEA, Grenoble-INP, IRIG, Pheliqs, 38000 Grenoble, France
| | - G Lapertot
- Université Grenoble Alpes, CEA, Grenoble-INP, IRIG, Pheliqs, 38000 Grenoble, France
| | - S Krämer
- Laboratoire National des Champs Magnétiques Intenses, LNCMI-CNRS (UPR3228), EMFL, Université Grenoble Alpes, UPS and INSA Toulouse, Boîte Postale 166, 38042 Grenoble Cedex 9, France
| | - M Horvatić
- Laboratoire National des Champs Magnétiques Intenses, LNCMI-CNRS (UPR3228), EMFL, Université Grenoble Alpes, UPS and INSA Toulouse, Boîte Postale 166, 38042 Grenoble Cedex 9, France
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2
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Sakai H, Tokiwa Y, Opletal P, Kimata M, Awaji S, Sasaki T, Aoki D, Kambe S, Tokunaga Y, Haga Y. Field Induced Multiple Superconducting Phases in UTe_{2} along Hard Magnetic Axis. PHYSICAL REVIEW LETTERS 2023; 130:196002. [PMID: 37243663 DOI: 10.1103/physrevlett.130.196002] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/19/2022] [Accepted: 04/04/2023] [Indexed: 05/29/2023]
Abstract
The superconducting (SC) phase diagram in uranium ditelluride is explored under magnetic fields (H) along the hard magnetic b axis using a high-quality single crystal with T_{c}=2.1 K. Simultaneous electrical resistivity and ac magnetic susceptibility measurements discern low- and high-field SC (LFSC and HFSC, respectively) phases with contrasting field-angular dependence. Crystal quality increases the upper critical field of the LFSC phase, but the H^{*} of ∼15 T, at which the HFSC phase appears, is always the same through the various crystals. A phase boundary signature is also observed inside the LFSC phase near H^{*}, indicating an intermediate SC phase characterized by small flux pinning forces.
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Affiliation(s)
- H Sakai
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Y Tokiwa
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - P Opletal
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - M Kimata
- Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - S Awaji
- High Field Laboratory for Superconducting Materials, Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - T Sasaki
- Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - D Aoki
- Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan
| | - S Kambe
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Y Tokunaga
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Y Haga
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
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3
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Aoki D, Brison JP, Flouquet J, Ishida K, Knebel G, Tokunaga Y, Yanase Y. Unconventional superconductivity in UTe 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:243002. [PMID: 35203074 DOI: 10.1088/1361-648x/ac5863] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 02/24/2022] [Indexed: 06/14/2023]
Abstract
The novel spin-triplet superconductor candidate UTe2was discovered only recently at the end of 2018 and already attracted enormous attention. We review key experimental and theoretical progress which has been achieved in different laboratories. UTe2is a heavy-fermion paramagnet, but following the discovery of superconductivity, it has been expected to be close to a ferromagnetic instability, showing many similarities to the U-based ferromagnetic superconductors, URhGe and UCoGe. This view might be too simplistic. The competition between different types of magnetic interactions and the duality between the local and itinerant character of the 5fUranium electrons, as well as the shift of the U valence appear as key parameters in the rich phase diagrams discovered recently under extreme conditions like low temperature, high magnetic field, and pressure. We discuss macroscopic and microscopic experiments at low temperature to clarify the normal phase properties at ambient pressure for field applied along the three axis of this orthorhombic structure. Special attention will be given to the occurrence of a metamagnetic transition atHm= 35 T for a magnetic field applied along the hard magnetic axisb. Adding external pressure leads to strong changes in the magnetic and electronic properties with a direct feedback on superconductivity. Attention is paid on the possible evolution of the Fermi surface as a function of magnetic field and pressure. Superconductivity in UTe2is extremely rich, exhibiting various unconventional behaviors which will be highlighted. It shows an exceptionally huge superconducting upper critical field with a re-entrant behavior under magnetic field and the occurrence of multiple superconducting phases in the temperature-field-pressure phase diagrams. There is evidence for spin-triplet pairing. Experimental indications exist for chiral superconductivity and spontaneous time reversal symmetry breaking in the superconducting state. Different theoretical approaches will be described. Notably we discuss that UTe2is a possible example for the realization of a fascinating topological superconductor. Exploring superconductivity in UTe2reemphasizes that U-based heavy fermion compounds give unique examples to study and understand the strong interplay between the normal and superconducting properties in strongly correlated electron systems.
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Affiliation(s)
- D Aoki
- IMR, Tohoku University, Oarai, Ibaraki, 311-1313, Japan
| | - J-P Brison
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, F-38000 Grenoble, France
| | - J Flouquet
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, F-38000 Grenoble, France
| | - K Ishida
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - G Knebel
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, F-38000 Grenoble, France
| | - Y Tokunaga
- ASRC, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Y Yanase
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
- Institute for Molecular Science, Okazaki 444-8585, Japan
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4
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Zhu HJ, Xu K, Zhang GF, Liu WM. Finite-Component Multicriticality at the Superradiant Quantum Phase Transition. PHYSICAL REVIEW LETTERS 2020; 125:050402. [PMID: 32794842 DOI: 10.1103/physrevlett.125.050402] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 07/08/2020] [Indexed: 06/11/2023]
Abstract
We demonstrate the existence of finite-component multicriticality in a qubit-boson model where biased qubits collectively coupled to a single-mode bosonic field. The interplay between biases and boson-qubit coupling produces a rich phase diagram which shows multiple superradiant phases and phase boundaries of different orders. In particular, multiple phases become indistinguishable in appropriate bias configurations, which is the signature of multicriticality. A series of universality classes characterizing these multicritical points are identified. Moreover, we present a trapped-ion realization with the potential to explore multicritical phenomena experimentally using a small number of ions. The results open a novel way to probe multicritical universality classes in experiments.
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Affiliation(s)
- Han-Jie Zhu
- Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), School of Physics, Beihang University, Xueyuan Road No. 37, Beijing 100191, China
| | - Kai Xu
- Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), School of Physics, Beihang University, Xueyuan Road No. 37, Beijing 100191, China
| | - Guo-Feng Zhang
- Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), School of Physics, Beihang University, Xueyuan Road No. 37, Beijing 100191, China
| | - Wu-Ming Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
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Tateiwa N, Haga Y, Yamamoto E. Strong Correlation between Ferromagnetic Superconductivity and Pressure-enhanced Ferromagnetic Fluctuations in UGe_{2}. PHYSICAL REVIEW LETTERS 2018; 121:237001. [PMID: 30576177 DOI: 10.1103/physrevlett.121.237001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 10/29/2018] [Indexed: 06/09/2023]
Abstract
We have measured magnetization at high pressure in the uranium ferromagnetic superconductor UGe_{2} and analyzed the magnetic data using Takahashi's spin fluctuation theory. There is a peak in the pressure dependence of the width of the spin fluctuation spectrum in the energy space T_{0} at P_{x}, the phase boundary of FM1 and FM2 where the superconducting transition temperature T_{sc} is highest. This suggests a clear correlation between the superconductivity and pressure-enhanced magnetic fluctuations developed at P_{x}. The pressure effect on T_{Curie}/T_{0}, where T_{Curie} is the Curie temperature, suggests that the less itinerant ferromagnetic state FM2 is changed to a more itinerant one FM1 across P_{x}. Peculiar features in relations between T_{0} and T_{sc} in uranium ferromagnetic superconductors UGe_{2}, URhGe, and UCoGe are discussed in comparison with those in high-T_{c} cuprate and heavy fermion superconductors.
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Affiliation(s)
- Naoyuki Tateiwa
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195, Japan
| | - Yoshinori Haga
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195, Japan
| | - Etsuji Yamamoto
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195, Japan
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6
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Sherkunov Y, Chubukov AV, Betouras JJ. Effects of Lifshitz Transitions in Ferromagnetic Superconductors: The Case of URhGe. PHYSICAL REVIEW LETTERS 2018; 121:097001. [PMID: 30230897 DOI: 10.1103/physrevlett.121.097001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Indexed: 06/08/2023]
Abstract
In ferromagnetic superconductors, like URhGe, superconductivity coexists with magnetism near zero field, but then reappears in a finite field range, where the system also displays mass enhancement in the normal state. We present the theoretical understanding of this nonmonotonic behavior. We explore the multiband nature of URhGe and associate reentrant superconductivity and mass enhancement with the topological transition (Lifshitz) in one of the bands in a finite magnetic field. We find excellent agreement between our theory and a number of experimental results for URhGe, such as weakly first-order reentrant transition, the dependence of superconducting T_{c} on a magnetic field, and the field dependence of the effective mass, the specific heat, and the resistivity in the normal state. Our theory can be applied to other ferromagnetic multiband superconductors.
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Affiliation(s)
- Yury Sherkunov
- Department of Physics and Centre for the Science of Materials, Loughborough University, Loughborough, LE11 3TU, United Kingdom
| | - Andrey V Chubukov
- Department of Physics, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Joseph J Betouras
- Department of Physics and Centre for the Science of Materials, Loughborough University, Loughborough, LE11 3TU, United Kingdom
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7
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Mao Q, Yang J, Wang H, Chen B, Geng X, Pan M, Fang M. From tricritical ferromagnetism to metamagnetism in quasi-two dimensional Tl(Co 1-x Ni x ) 2S 2 (x = 0, 0.05). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:295801. [PMID: 29889045 DOI: 10.1088/1361-648x/aacbb4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We have investigated the critical behavior near the ferromagnetic transition of TlCo2S2 single crystals and the magnetic properties of Tl(Co0.95Ni0.05)2S2 by means of magnetization measurements. The obtained critical exponents β, γ and δ of TlCo2S2 could basically satisfy the scaling equations and are found very close to the prediction of the tricritical mean-field theory. 5[Formula: see text] Ni doping drives the system to an antiferromagnetic ground state which is unstable to magnetic field, yielding metamagnetic transition. The possible existence of a tricritical point (TCP) in Tl(Co0.95Ni0.05)2S2 is also discussed.
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Affiliation(s)
- Qianhui Mao
- College of Science, Henan Institute of Engineering, Xinzheng 451191, People's Republic of China. Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
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8
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Braithwaite D, Aoki D, Brison JP, Flouquet J, Knebel G, Nakamura A, Pourret A. Dimensionality Driven Enhancement of Ferromagnetic Superconductivity in URhGe. PHYSICAL REVIEW LETTERS 2018; 120:037001. [PMID: 29400517 DOI: 10.1103/physrevlett.120.037001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Indexed: 06/07/2023]
Abstract
In most unconventional superconductors, like the high-T_{c} cuprates, iron pnictides, or heavy-fermion systems, superconductivity emerges in the proximity of an electronic instability. Identifying unambiguously the pairing mechanism remains nevertheless an enormous challenge. Among these systems, the orthorhombic uranium ferromagnetic superconductors have a unique position, notably because magnetic fields couple directly to ferromagnetic order, leading to the fascinating discovery of the reemergence of superconductivity in URhGe at a high field. Here we show that uniaxial stress is a remarkable tool allowing the fine-tuning of the pairing strength. With a relatively small stress, the superconducting phase diagram is spectacularly modified, with a merging of the low- and high-field superconducting states and a significant enhancement of the superconductivity. The superconducting critical temperature increases both at zero field and under a field, reaching 1 K, more than twice higher than at ambient pressure. This enhancement of superconductivity is shown to be directly related to a change of the magnetic dimensionality detected from an increase of the transverse magnetic susceptibility: In addition to the Ising-type longitudinal ferromagnetic fluctuations, transverse magnetic fluctuations also play an important role in the superconducting pairing.
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Affiliation(s)
| | - Dai Aoki
- Université Grenoble Alpes, CEA, INAC-PHELIQS, 38000 Grenoble, France
- Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan
| | | | - Jacques Flouquet
- Université Grenoble Alpes, CEA, INAC-PHELIQS, 38000 Grenoble, France
| | - Georg Knebel
- Université Grenoble Alpes, CEA, INAC-PHELIQS, 38000 Grenoble, France
| | - Ai Nakamura
- Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan
| | - Alexandre Pourret
- Université Grenoble Alpes, CEA, INAC-PHELIQS, 38000 Grenoble, France
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9
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Martone GI, Pepe FV, Facchi P, Pascazio S, Stringari S. Tricriticalities and Quantum Phases in Spin-Orbit-Coupled Spin-1 Bose Gases. PHYSICAL REVIEW LETTERS 2016; 117:125301. [PMID: 27689283 DOI: 10.1103/physrevlett.117.125301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Indexed: 06/06/2023]
Abstract
We study the zero-temperature phase diagram of a spin-orbit-coupled Bose-Einstein condensate of spin 1, with equally weighted Rashba and Dresselhaus couplings. Depending on the antiferromagnetic or ferromagnetic nature of the interactions, we find three kinds of striped phases with qualitatively different behaviors in the modulations of the density profiles. Phase transitions to the zero-momentum and the plane-wave phases can be induced in experiments by independently varying the Raman coupling strength and the quadratic Zeeman field. The properties of these transitions are investigated in detail, and the emergence of tricritical points, which are the direct consequence of the spin-dependent interactions, is explicitly discussed.
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Affiliation(s)
- Giovanni I Martone
- Dipartimento di Fisica and MECENAS, Università di Bari, I-70126 Bari, Italy
- Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Bari, I-70126 Bari, Italy
| | - Francesco V Pepe
- Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Bari, I-70126 Bari, Italy
- Museo Storico della Fisica e Centro Studi e Ricerche "Enrico Fermi", I-00184 Roma, Italy
| | - Paolo Facchi
- Dipartimento di Fisica and MECENAS, Università di Bari, I-70126 Bari, Italy
- Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Bari, I-70126 Bari, Italy
| | - Saverio Pascazio
- Dipartimento di Fisica and MECENAS, Università di Bari, I-70126 Bari, Italy
- Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Bari, I-70126 Bari, Italy
| | - Sandro Stringari
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, I-38123 Povo, Italy
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Gourgout A, Pourret A, Knebel G, Aoki D, Seyfarth G, Flouquet J. Collapse of Ferromagnetism and Fermi Surface Instability near Reentrant Superconductivity of URhGe. PHYSICAL REVIEW LETTERS 2016; 117:046401. [PMID: 27494485 DOI: 10.1103/physrevlett.117.046401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Indexed: 06/06/2023]
Abstract
We present thermoelectric power and resistivity measurements in the ferromagnetic superconductor URhGe for a magnetic field applied along the hard magnetization b axis of the orthorhombic crystal. Reentrant superconductivity is observed near the spin reorientation transition at H_{R}=12.75 T, where a first order transition from the ferromagnetic to the polarized paramagnetic state occurs. Special focus is given to the longitudinal configuration, where both the electric and heat current are parallel to the applied field. The validity of the Fermi-liquid T^{2} dependence of the resistivity through H_{R} demonstrates clearly that no quantum critical point occurs at H_{R}. Thus, the ferromagnetic transition line at H_{R} becomes first order implying the existence of a tricritical point at finite temperature. The enhancement of magnetic fluctuations in the vicinity of the tricritical point stimulates the reentrance of superconductivity. The abrupt sign change observed in the thermoelectric power with the thermal gradient applied along the b axis together with the strong anomalies in the other directions is definitive macroscopic evidence that in addition a significant change of the Fermi surface appears through H_{R}.
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Affiliation(s)
- A Gourgout
- University Grenoble Alpes, INAC-PHELIQS, F-38000 Grenoble, France
- CEA, INAC-PHELIQS, F-38000 Grenoble, France
| | - A Pourret
- University Grenoble Alpes, INAC-PHELIQS, F-38000 Grenoble, France
- CEA, INAC-PHELIQS, F-38000 Grenoble, France
| | - G Knebel
- University Grenoble Alpes, INAC-PHELIQS, F-38000 Grenoble, France
- CEA, INAC-PHELIQS, F-38000 Grenoble, France
| | - D Aoki
- University Grenoble Alpes, INAC-PHELIQS, F-38000 Grenoble, France
- CEA, INAC-PHELIQS, F-38000 Grenoble, France
- Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan
| | - G Seyfarth
- University Grenoble Alpes, LNCMI, F-38042 Grenoble Cedex 9, France
- CNRS, Laboratoire National des Champs Magnétiques Intenses LNCMI (UJF, UPS, INSA), UPR 3228, F-38042 Grenoble Cedex 9, France
| | - J Flouquet
- University Grenoble Alpes, INAC-PHELIQS, F-38000 Grenoble, France
- CEA, INAC-PHELIQS, F-38000 Grenoble, France
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