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Kumar R, Luo SS, Du F, Su H, Zhang J, Cao C, Yuan HQ. Superconductivity in non-centrosymmetric ZrNiAl and HfRhSn-type compounds. J Phys Condens Matter 2022; 34:435701. [PMID: 35977535 DOI: 10.1088/1361-648x/ac8a80] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 08/17/2022] [Indexed: 06/15/2023]
Abstract
We report the discovery of superconductivity in non-centrosymmetric compounds HfNiAl, ZrNiAl, ZrNiGa, and HfPtAl by measuring their electrical transport and thermodynamic properties. HfNiAl, ZrNiAl, and ZrNiGa crystallize in the ZrNiAl-type crystal structure, whereas HfPtAl crystallizes in the HfRhSn-type crystal structure. Superconducting transitions for HfNiAl, ZrNiAl, ZrNiGa, and HfPtAl are observed at 1.0 K, 1.0 K, 0.42 K, and 0.58 K, respectively. Using the Werthamer-Helfand-Hohenberg model, the zero-temperature upper critical fieldsµ0Hc2(0) were estimated to be 0.58 T, 0.24 T, 0.08 T, and 0.34 T for HfNiAl, ZrNiAl, ZrNiGa, and HfPtAl, respectively. The observed jump in electronic heat capacity (ΔCe/γT) across the superconducting transition is 1.3, 1.3, and 1.2 for HfNiAl, ZrNiAl, and HfPtAl, respectively. After the inclusion of the spin-orbit coupling in the band structure calculations, a total of six bands for ZrNiAl, HfPtAl, and ZrNiGa, and eight bands for HfNiAl were found to cross the Fermi level. Spin-orbit coupling induced maximum splitting (ΔEASOC/kBTc) of the electronic bands near the Fermi level was found to be 1697, 517, 1138, and 4230 for HfNiAl, ZrNiAl, ZrNiGa, and HfPtAl, respectively. Large variation of the antisymmetric spin-orbit coupling (ASOC) among these compounds provides a great opportunity to study the effects of ASOC on the superconducting pairing states.
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Affiliation(s)
- Rohit Kumar
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Shuai-Shuai Luo
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Feng Du
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Hang Su
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Jiawen Zhang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Chao Cao
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - H Q Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
- State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310058, People's Republic of China
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Zhang L, Yuan HQ. Antisolvent Crystallization Method and Mixed Solvent Solubility Model Study of 2-Chloro-4,6-Dinitroresorcinol. Theor Found Chem Eng 2021. [DOI: 10.1134/s0040579521010176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Shang T, Smidman M, Wang A, Chang LJ, Baines C, Lee MK, Nie ZY, Pang GM, Xie W, Jiang WB, Shi M, Medarde M, Shiroka T, Yuan HQ. Simultaneous Nodal Superconductivity and Time-Reversal Symmetry Breaking in the Noncentrosymmetric Superconductor CaPtAs. Phys Rev Lett 2020; 124:207001. [PMID: 32501078 DOI: 10.1103/physrevlett.124.207001] [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: 12/16/2019] [Revised: 03/12/2020] [Accepted: 04/21/2020] [Indexed: 06/11/2023]
Abstract
By employing a series of experimental techniques, we provide clear evidence that CaPtAs represents a rare example of a noncentrosymmetric superconductor which simultaneously exhibits nodes in the superconducting gap and broken time-reversal symmetry (TRS) in its superconducting state (below T_{c}≈1.5 K). Unlike in fully gapped superconductors, the magnetic penetration depth λ(T) does not saturate at low temperatures, but instead it shows a T^{2} dependence, characteristic of gap nodes. Both the superfluid density and the electronic specific heat are best described by a two-gap model comprising of a nodeless gap and a gap with nodes, rather than by single-band models. At the same time, zero-field muon-spin relaxation spectra exhibit increased relaxation rates below the onset of superconductivity, implying that TRS is broken in the superconducting state of CaPtAs, hence indicating its unconventional nature. Our observations suggest CaPtAs to be a new remarkable material that links two apparently disparate classes, that of TRS-breaking correlated magnetic superconductors with nodal gaps and the weakly correlated noncentrosymmetric superconductors with broken TRS, normally exhibiting only a fully gapped behavior.
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Affiliation(s)
- T Shang
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, Villigen CH-5232, Switzerland
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, Zürich CH-8057, Switzerland
| | - M Smidman
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - A Wang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - L-J Chang
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
| | - C Baines
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, Villigen PSI CH-5232, Switzerland
| | - M K Lee
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
| | - Z Y Nie
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - G M Pang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - W Xie
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - W B Jiang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, Villigen CH-5232, Switzerland
| | - M Medarde
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, Villigen CH-5232, Switzerland
| | - T Shiroka
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, Villigen PSI CH-5232, Switzerland
- Laboratorium für Festkörperphysik, ETH Zürich, Zürich CH-8093, Switzerland
| | - H Q Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing Univeristy, Nanjing 210093, China
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Liu YP, Zhang YJ, Dong JJ, Lee H, Wei ZX, Zhang WL, Chen CY, Yuan HQ, Yang YF, Qi J. Hybridization Dynamics in CeCoIn_{5} Revealed by Ultrafast Optical Spectroscopy. Phys Rev Lett 2020; 124:057404. [PMID: 32083911 DOI: 10.1103/physrevlett.124.057404] [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: 06/19/2019] [Revised: 01/14/2020] [Accepted: 01/15/2020] [Indexed: 06/10/2023]
Abstract
We investigate the quasiparticle dynamics in the prototypical heavy fermion CeCoIn_{5} using ultrafast optical pump-probe spectroscopy. Our results indicate that this material system undergoes hybridization fluctuations before the establishment of heavy electron coherence, as the temperature decreases from ∼120 K (T^{†}) to ∼55 K (T^{*}). We reveal that the anomalous coherent phonon softening and damping reduction below T^{*} are directly associated with the emergence of collective hybridization. We also discover a distinct collective mode with an energy of ∼8 meV, which may be experimental evidence of the predicted unconventional density wave. Our findings provide important information for understanding the hybridization dynamics in heavy fermion systems.
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Affiliation(s)
- Y P Liu
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 611731, China
- Institute of Modern Physics, Fudan University, Shanghai 200433, China
| | - Y J Zhang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - J J Dong
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - H Lee
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - Z X Wei
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 611731, China
- Institute of Electronic and Information Engineering, University of Electronic Science and Technology of China, Dongguan 523808, China
| | - W L Zhang
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - C Y Chen
- Institute of Modern Physics, Fudan University, Shanghai 200433, China
| | - H Q Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - Yi-Feng Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan 523808, China
| | - J Qi
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 611731, China
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Shang T, Smidman M, Ghosh SK, Baines C, Chang LJ, Gawryluk DJ, Barker JAT, Singh RP, Paul DM, Balakrishnan G, Pomjakushina E, Shi M, Medarde M, Hillier AD, Yuan HQ, Quintanilla J, Mesot J, Shiroka T. Time-Reversal Symmetry Breaking in Re-Based Superconductors. Phys Rev Lett 2018; 121:257002. [PMID: 30608781 DOI: 10.1103/physrevlett.121.257002] [Citation(s) in RCA: 2] [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: 03/11/2018] [Revised: 07/30/2018] [Indexed: 06/09/2023]
Abstract
To trace the origin of time-reversal symmetry breaking (TRSB) in Re-based superconductors, we performed comparative muon-spin rotation and relaxation (μSR) studies of superconducting noncentrosymmetric Re_{0.82}Nb_{0.18} (T_{c}=8.8 K) and centrosymmetric Re (T_{c}=2.7 K). In Re_{0.82}Nb_{0.18}, the low-temperature superfluid density and the electronic specific heat evidence a fully gapped superconducting state, whose enhanced gap magnitude and specific-heat discontinuity suggest a moderately strong electron-phonon coupling. In both Re_{0.82}Nb_{0.18} and pure Re, the spontaneous magnetic fields revealed by zero-field μSR below T_{c} indicate time-reversal symmetry breaking and thus unconventional superconductivity. The concomitant occurrence of TRSB in centrosymmetric Re and noncentrosymmetric ReT (T=transition metal), yet its preservation in the isostructural noncentrosymmetric superconductors Mg_{10}Ir_{19}B_{16} and Nb_{0.5}Os_{0.5}, strongly suggests that the local electronic structure of Re is crucial for understanding the TRSB superconducting state in Re and ReT. We discuss the superconducting order parameter symmetries that are compatible with the experimental observations.
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Affiliation(s)
- T Shang
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, Villigen CH-5232, Switzerland
- Swiss Light Source, Paul Scherrer Institut, Villigen CH-5232, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - M Smidman
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - S K Ghosh
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - C Baines
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - L J Chang
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
| | - D J Gawryluk
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, Villigen CH-5232, Switzerland
| | - J A T Barker
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - R P Singh
- Indian Institute of Science Education and Research Bhopal, Bhopal, 462066, India
| | - D McK Paul
- Physics Department, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - G Balakrishnan
- Physics Department, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - E Pomjakushina
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, Villigen CH-5232, Switzerland
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, Villigen CH-5232, Switzerland
| | - M Medarde
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, Villigen CH-5232, Switzerland
| | - A D Hillier
- ISIS Facility, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Oxfordshire, OX11 0QX, United Kingdom
| | - H Q Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing Univeristy, Nanjing 210093, China
| | - J Quintanilla
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - J Mesot
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
- Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zurich, Switzerland
| | - T Shiroka
- Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zurich, Switzerland
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Guo CY, Wu F, Wu ZZ, Smidman M, Cao C, Bostwick A, Jozwiak C, Rotenberg E, Liu Y, Steglich F, Yuan HQ. Evidence for Weyl fermions in a canonical heavy-fermion semimetal YbPtBi. Nat Commun 2018; 9:4622. [PMID: 30397192 PMCID: PMC6218469 DOI: 10.1038/s41467-018-06782-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Accepted: 09/25/2018] [Indexed: 11/08/2022] Open
Abstract
The manifestation of Weyl fermions in strongly correlated electron systems is of particular interest. We report evidence for Weyl fermions in the heavy fermion semimetal YbPtBi from electronic structure calculations, angle-resolved photoemission spectroscopy, magnetotransport and calorimetric measurements. At elevated temperatures where 4f-electrons are localized, there are triply degenerate points, yielding Weyl nodes in applied magnetic fields. These are revealed by a contribution from the chiral anomaly in the magnetotransport, which at low temperatures becomes negligible due to the influence of electronic correlations. Instead, Weyl fermions are inferred from the topological Hall effect, which provides evidence for a Berry curvature, and a cubic temperature dependence of the specific heat, as expected from the linear dispersion near the Weyl nodes. The results suggest that YbPtBi is a Weyl heavy fermion semimetal, where the Kondo interaction renormalizes the bands hosting Weyl points. These findings open up an opportunity to explore the interplay between topology and strong electronic correlations.
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Affiliation(s)
- C Y Guo
- Center for Correlated Matter and Department of Physics, Zhejiang University, 310058, Hangzhou, China
| | - F Wu
- Center for Correlated Matter and Department of Physics, Zhejiang University, 310058, Hangzhou, China
| | - Z Z Wu
- Center for Correlated Matter and Department of Physics, Zhejiang University, 310058, Hangzhou, China
| | - M Smidman
- Center for Correlated Matter and Department of Physics, Zhejiang University, 310058, Hangzhou, China
| | - C Cao
- Department of Physics, Hangzhou Normal University, 310036, Hangzhou, China
| | - A Bostwick
- Advanced Light Source, E.O. Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA
| | - C Jozwiak
- Advanced Light Source, E.O. Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA
| | - E Rotenberg
- Advanced Light Source, E.O. Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA
| | - Y Liu
- Center for Correlated Matter and Department of Physics, Zhejiang University, 310058, Hangzhou, China
| | - F Steglich
- Center for Correlated Matter and Department of Physics, Zhejiang University, 310058, Hangzhou, China
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - H Q Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, 310058, Hangzhou, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093, Nanjing, China.
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Zhang YJ, Xia XB, Jiang WB, Wang YF, Liu JY, Yuan HQ, Lee H. Single crystal growth and anisotropic physical properties of Sm 4Co 3Ga 16. J Phys Condens Matter 2018; 30:345701. [PMID: 30010612 DOI: 10.1088/1361-648x/aad39c] [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] [Indexed: 06/08/2023]
Abstract
We have synthesized high quality single crystals of Sm4Co3Ga16 with gallium flux and investigated its physical properties with electrical resistivity, magnetization and specific-heat measurements. Antiferromagnetic transition below 6.7 K has been detected. No superconducting transitions have been dectected down to 0.5 K from our single crystals. Based on our experimental result, Sm3+ state in Sm4Co3Ga16 is likely well localized, in which stable magnetic moment in its doubly degenerated ground state contributes to the magnetic order with little interference of Kondo type of interaction.
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Affiliation(s)
- Y J Zhang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
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Chen QY, Xu DF, Niu XH, Peng R, Xu HC, Wen CHP, Liu X, Shu L, Tan SY, Lai XC, Zhang YJ, Lee H, Strocov VN, Bisti F, Dudin P, Zhu JX, Yuan HQ, Kirchner S, Feng DL. Band Dependent Interlayer f-Electron Hybridization in CeRhIn_{5}. Phys Rev Lett 2018; 120:066403. [PMID: 29481263 DOI: 10.1103/physrevlett.120.066403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 01/02/2018] [Indexed: 06/08/2023]
Abstract
A key issue in heavy fermion research is how subtle changes in the hybridization between the 4f (5f) and conduction electrons can result in fundamentally different ground states. CeRhIn_{5} stands out as a particularly notable example: when replacing Rh with either Co or Ir, antiferromagnetism gives way to superconductivity. In this photoemission study of CeRhIn_{5}, we demonstrate that the use of resonant angle-resolved photoemission spectroscopy with polarized light allows us to extract detailed information on the 4f crystal field states and details on the 4f and conduction electron hybridization, which together determine the ground state. We directly observe weakly dispersive Kondo resonances of f electrons and identify two of the three Ce 4f_{5/2}^{1} crystal-electric-field levels and band-dependent hybridization, which signals that the hybridization occurs primarily between the Ce 4f states in the CeIn_{3} layer and two more three-dimensional bands composed of the Rh 4d and In 5p orbitals in the RhIn_{2} layer. Our results allow us to connect the properties observed at elevated temperatures with the unusual low-temperature properties of this enigmatic heavy fermion compound.
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Affiliation(s)
- Q Y Chen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621908, China
| | - D F Xu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - X H Niu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - R Peng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - H C Xu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - C H P Wen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - X Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - L Shu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - S Y Tan
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621908, China
| | - X C Lai
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621908, China
| | - Y J Zhang
- Center for Correlated Matter, Zhejiang University, Hangzhou 310058, China
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - H Lee
- Center for Correlated Matter, Zhejiang University, Hangzhou 310058, China
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - F Bisti
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - P Dudin
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - J-X Zhu
- Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - H Q Yuan
- Center for Correlated Matter, Zhejiang University, Hangzhou 310058, China
- Department of Physics, Zhejiang University, Hangzhou 310027, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - S Kirchner
- Center for Correlated Matter, Zhejiang University, Hangzhou 310058, China
| | - D L Feng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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Zhang JL, Guo CY, Zhu XD, Ma L, Zheng GL, Wang YQ, Pi L, Chen Y, Yuan HQ, Tian ML. Disruption of the Accidental Dirac Semimetal State in ZrTe_{5} under Hydrostatic Pressure. Phys Rev Lett 2017; 118:206601. [PMID: 28581794 DOI: 10.1103/physrevlett.118.206601] [Citation(s) in RCA: 2] [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: 01/11/2017] [Indexed: 06/07/2023]
Abstract
We study the effect of hydrostatic pressure on the magnetotransport properties of zirconium pentatelluride. The magnitude of resistivity anomaly gets enhanced with increasing pressure, but the transition temperature T^{*} is insensitive to it up to 2.5 GPa. In the case of H∥b, the quasilinear magnetoresistance decreases drastically from 3300% (9 T) at ambient pressure to 230% (9 T) at 2.5 GPa. Besides, the change of the quantum oscillation phase from topological nontrivial to trivial is revealed around 2 GPa. Both demonstrate that the pressure breaks the accidental Dirac node in ZrTe_{5}. For H∥c, in contrast, subtle changes can be seen in the magnetoresistance and quantum oscillations. In the presence of pressure, ZrTe_{5} evolves from a highly anisotropic to a nearly isotropic electronic system, which accompanies the disruption of the accidental Dirac semimetal state. It supports the assumption that ZrTe_{5} is a semi-3D Dirac system with linear dispersion along two directions and a quadratic one along the third.
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Affiliation(s)
- J L Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - C Y Guo
- Department of Physics and Center for Correlated Matter, Zhejiang University, Hangzhou 310027, Zhejiang, People's Republic of China
| | - X D Zhu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - L Ma
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - G L Zheng
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - Y Q Wang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - L Pi
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - Y Chen
- Department of Physics and Center for Correlated Matter, Zhejiang University, Hangzhou 310027, Zhejiang, People's Republic of China
| | - H Q Yuan
- Department of Physics and Center for Correlated Matter, Zhejiang University, Hangzhou 310027, Zhejiang, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - M L Tian
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
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10
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Smidman M, Salamon MB, Yuan HQ, Agterberg DF. Superconductivity and spin-orbit coupling in non-centrosymmetric materials: a review. Rep Prog Phys 2017; 80:036501. [PMID: 28072583 DOI: 10.1088/1361-6633/80/3/036501] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In non-centrosymmetric superconductors, where the crystal structure lacks a centre of inversion, parity is no longer a good quantum number and an electronic antisymmetric spin-orbit coupling (ASOC) is allowed to exist by symmetry. If this ASOC is sufficiently large, it has profound consequences on the superconducting state. For example, it generally leads to a superconducting pairing state which is a mixture of spin-singlet and spin-triplet components. The possibility of such novel pairing states, as well as the potential for observing a variety of unusual behaviors, led to intensive theoretical and experimental investigations. Here we review the experimental and theoretical results for superconducting systems lacking inversion symmetry. Firstly we give a conceptual overview of the key theoretical results. We then review the experimental properties of both strongly and weakly correlated bulk materials, as well as two dimensional systems. Here the focus is on evaluating the effects of ASOC on the superconducting properties and the extent to which there is evidence for singlet-triplet mixing. This is followed by a more detailed overview of theoretical aspects of non-centrosymmetric superconductivity. This includes the effects of the ASOC on the pairing symmetry and the superconducting magnetic response, magneto-electric effects, superconducting finite momentum pairing states, and the potential for non-centrosymmetric superconductors to display topological superconductivity.
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Affiliation(s)
- M Smidman
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
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Weng ZF, Smidman M, Jiao L, Lu X, Yuan HQ. Multiple quantum phase transitions and superconductivity in Ce-based heavy fermions. Rep Prog Phys 2016; 79:094503. [PMID: 27533524 DOI: 10.1088/0034-4885/79/9/094503] [Citation(s) in RCA: 2] [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] [Indexed: 06/06/2023]
Abstract
Heavy fermions have served as prototype examples of strongly-correlated electron systems. The occurrence of unconventional superconductivity in close proximity to the electronic instabilities associated with various degrees of freedom points to an intricate relationship between superconductivity and other electronic states, which is unique but also shares some common features with high temperature superconductivity. The magnetic order in heavy fermion compounds can be continuously suppressed by tuning external parameters to a quantum critical point, and the role of quantum criticality in determining the properties of heavy fermion systems is an important unresolved issue. Here we review the recent progress of studies on Ce based heavy fermion superconductors, with an emphasis on the superconductivity emerging on the edge of magnetic and charge instabilities as well as the quantum phase transitions which occur by tuning different parameters, such as pressure, magnetic field and doping. We discuss systems where multiple quantum critical points occur and whether they can be classified in a unified manner, in particular in terms of the evolution of the Fermi surface topology.
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Affiliation(s)
- Z F Weng
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
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12
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Weng ZF, Zhang JL, Smidman M, Shang T, Quintanilla J, Annett JF, Nicklas M, Pang GM, Jiao L, Jiang WB, Chen Y, Steglich F, Yuan HQ. Two-Gap Superconductivity in LaNiGa_{2} with Nonunitary Triplet Pairing and Even Parity Gap Symmetry. Phys Rev Lett 2016; 117:027001. [PMID: 27447519 DOI: 10.1103/physrevlett.117.027001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Indexed: 06/06/2023]
Abstract
The nature of the pairing states of superconducting LaNiC_{2} and LaNiGa_{2} has to date remained a puzzling question. Broken time reversal symmetry has been observed in both compounds and a group theoretical analysis implies a nonunitary triplet pairing state. However, all the allowed nonunitary triplet states have nodal gap functions but most thermodynamic and NMR measurements indicate fully gapped superconductivity in LaNiC_{2}. Here we probe the gap symmetry of LaNiGa_{2} by measuring the London penetration depth, specific heat, and upper critical field. These measurements demonstrate two-gap nodeless superconductivity in LaNiGa_{2}, suggesting that this is a common feature of both compounds. These results allow us to propose a novel triplet superconducting state, where the pairing occurs between electrons of the same spin, but on different orbitals. In this case the superconducting wave function has a triplet spin component but isotropic even parity gap symmetry, yet the overall wave function remains antisymmetric under particle exchange. This model leads to a nodeless two-gap superconducting state which breaks time reversal symmetry, and therefore accounts well for the seemingly contradictory experimental results.
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Affiliation(s)
- Z F Weng
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - J L Zhang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - M Smidman
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - T Shang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - J Quintanilla
- SEPnet and Hubbard Theory Consortium, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - J F Annett
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - M Nicklas
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - G M Pang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - L Jiao
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - W B Jiang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - Y Chen
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - F Steglich
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - H Q Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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13
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Jiang WB, Yang L, Guo CY, Hu Z, Lee JM, Smidman M, Wang YF, Shang T, Cheng ZW, Gao F, Ishii H, Tsuei KD, Liao YF, Lu X, Tjeng LH, Chen JM, Yuan HQ. Crossover from a heavy fermion to intermediate valence state in noncentrosymmetric Yb2Ni12(P,As)7. Sci Rep 2015; 5:17608. [PMID: 26626431 PMCID: PMC4667268 DOI: 10.1038/srep17608] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 11/03/2015] [Indexed: 11/16/2022] Open
Abstract
We report measurements of the physical properties and electronic structure of the hexagonal compounds Yb2Ni12Pn7 (Pn = P, As) by measuring the electrical resistivity, magnetization, specific heat and partial fluorescence yield x-ray absorption spectroscopy (PFY-XAS). These demonstrate a crossover upon reducing the unit cell volume, from an intermediate valence state in Yb2Ni12As7 to a heavy-fermion paramagnetic state in Yb2Ni12P7, where the Yb is nearly trivalent. Application of pressure to Yb2Ni12P7 suppresses TFL, the temperature below which Fermi liquid behavior is recovered, suggesting the presence of a quantum critical point (QCP) under pressure. However, while there is little change in the Yb valence of Yb2Ni12P7 up to 30 GPa, there is a strong increase for Yb2Ni12As7 under pressure, before a near constant value is reached. These results indicate that any magnetic QCP in this system is well separated from strong valence fluctuations. The pressure dependence of the valence and lattice parameters of Yb2Ni12As7 are compared and at 1 GPa, there is an anomaly in the unit cell volume as well as a change in the slope of the Yb valence, indicating a correlation between structural and electronic changes.
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Affiliation(s)
- W B Jiang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China
| | - L Yang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China
| | - C Y Guo
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China
| | - Z Hu
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - J M Lee
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - M Smidman
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China
| | - Y F Wang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China
| | - T Shang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China
| | - Z W Cheng
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China
| | - F Gao
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China
| | - H Ishii
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - K D Tsuei
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Y F Liao
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - X Lu
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - L H Tjeng
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - J M Chen
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - H Q Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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14
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Jiao L, Weng Z, Liu J, Zhang J, Pang G, Guo C, Gao F, Zhu X, Wen HH, Yuan HQ. Evidence for nodeless superconductivity in NdO(1-x)F(x)BiS2 (x = 0.3 and 0.5) single crystals. J Phys Condens Matter 2015; 27:225701. [PMID: 25988300 DOI: 10.1088/0953-8984/27/22/225701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We study the superconducting pairing states of NdO(1-x)F(x)BiS2 (x = 0.3 and 0.5) by measuring the magnetic penetration depth Δλ(T) using the tunnel-diode-oscillator (TDO) technique. An upturn is observed in Δλ(T) as well as the magnetic susceptibility χ(T) in the low-temperature limit, which is attributed to the paramagnetism of Nd ions. After subtracting the paramagnetic contributions, the penetration depth Δλ(T) follows an exponential-type temperature dependence at T ≪ T(c), providing evidence of nodeless superconductivity for NdO(1-x)F(x)BiS2. This is further supported by the analyses of superfluid density ρ(s)(T), which can be well described by a BCS model with an energy gap of Δ(0) ∼ 2.15 k(B)T(c).
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Affiliation(s)
- Lin Jiao
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China
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15
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Chen Y, Jiang WB, Guo CY, Ronning F, Bauer ED, Park T, Yuan HQ, Fisk Z, Thompson JD, Lu X. Reemergent superconductivity and avoided quantum criticality in Cd-doped CeIrIn(5) under pressure. Phys Rev Lett 2015; 114:146403. [PMID: 25910144 DOI: 10.1103/physrevlett.114.146403] [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: 12/23/2014] [Indexed: 06/04/2023]
Abstract
We investigated the electrical resistivity and heat capacity of 1% Cd-doped CeIrIn_{5} under hydrostatic pressure up to 2.7 GPa, near where long-range antiferromagnetic order is suppressed and bulk superconductivity suddenly reemerges. The pressure-induced T_{c} is close to that of pristine CeIrIn_{5} at 2.7 GPa, and no signatures of a quantum critical point under pressure support a local origin of the antiferromagnetic moments in Cd-CeIrIn_{5} at ambient pressure. Similarities between superconductors CeIrIn_{5} and CeCoIn_{5} in response to Cd substitutions suggest a common magnetic mechanism.
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Affiliation(s)
- Y Chen
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - W B Jiang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - C Y Guo
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - F Ronning
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - E D Bauer
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Tuson Park
- Department of Physics, Sungkyunkwan University, Suwon 440-746, South Korea
| | - H Q Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Z Fisk
- Department of Physics, University of California, Irvine, California 92697, USA
| | - J D Thompson
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Xin Lu
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
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16
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Jiang WB, Guo CY, Weng ZF, Wang YF, Chen YH, Chen Y, Pang GM, Shang T, Lu X, Yuan HQ. Superconductivity and structural distortion in BaPt2As2. J Phys Condens Matter 2015; 27:022202. [PMID: 25483554 DOI: 10.1088/0953-8984/27/2/022202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report the synthesis of BaPt2As2 single crystals and the discovery of superconductivity and a structural phase transition in this compound by measuring the electrical resistivity, magnetic susceptibility and specific heat as well as the x-ray diffraction at low temperatures. BaPt2As2 crystallizes in the CaBe2Ge2-type tetragonal structure (P4/nmm) at room temperature and undergoes a first-order structural transition at TS ≃ 275 K, which is likely to be associated with a charge-density-wave (CDW) instability. BCS-like superconductivity with two subsequent transitions Tc1 ≃ 1.67 K and Tc2 ≃ 1.33 K is observed. Our results demonstrate that BaPt2As2 may serve as a new system for studying the interplay of superconductivity and the CDW order.
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Affiliation(s)
- W B Jiang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
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17
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Shang T, Chen YH, Jiang WB, Chen Y, Jiao L, Zhang JL, Weng ZF, Lu X, Yuan HQ. Tunable magnetic orders in CePd2As2-xPx. J Phys Condens Matter 2014; 26:045601. [PMID: 24355882 DOI: 10.1088/0953-8984/26/4/045601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report the successful synthesis of the polycrystalline compounds CePd2As2-xPx (0 ≤ x ≤ 2) and their physical properties by measuring transport, magnetic and thermodynamic behaviors as a function of temperature and/or magnetic field. Powder x-ray diffraction indicates that CePd2As2-xPx crystallizes in the ThCr2Si2-type tetragonal structure. CePd2As2 exhibits a moderate Sommerfeld coefficient of γ ≈ 88 mJ mol(-1) K(-2), and undergoes an antiferromagnetic (AFM) transition at the Néel temperature TN ≈ 15 K. Upon substituting As with P, the TN is nearly unchanged up to x ≃ 0.6, while a ferromagnetic (FM) transition develops below TN for x ≃ 0.4. The Curie temperature TC increases with increasing x and eventually merges with the AFM transition at x ≃ 0.6. With further increase of x, the system follows typical FM behaviors and its TC monotonically increases and reaches TC ≈ 28 K in CePd2P2. Moreover, a metamagnetic transition is observed in the As-rich samples, but vanishes for x ≥ 0.4. Such a tunable magnetic ground state may provide an opportunity to explore the possible quantum critical behavior in CePd2As2-xPx.
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Affiliation(s)
- T Shang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China
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18
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Yuan HQ, Jiao L, Singleton J, Balakirev FF, Chen GF, Luo JL, Wang NL. The magnetoresistance and Hall effect in CeFeAsO: a high magnetic field study. ACTA ACUST UNITED AC 2011. [DOI: 10.1088/1742-6596/273/1/012110] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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19
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Chia EEM, Talbayev D, Zhu JX, Yuan HQ, Park T, Thompson JD, Panagopoulos C, Chen GF, Luo JL, Wang NL, Taylor AJ. Ultrafast pump-probe study of phase separation and competing orders in the underdoped (Ba,K)Fe2As2 superconductor. Phys Rev Lett 2010; 104:027003. [PMID: 20366619 DOI: 10.1103/physrevlett.104.027003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Indexed: 05/29/2023]
Abstract
We report measurements of quasiparticle relaxation dynamics in the high-temperature superconductor (Ba,K)Fe2As2 in optimally doped, underdoped, and undoped regimes. In the underdoped sample, spin-density wave (SDW) order forms at approximately 85 K, followed by superconductivity at approximately 28 K. We find the emergence of a normal-state order that suppresses SDW at a temperature T{*} approximately 60 K and argue that this normal-state order is a precursor to superconductivity.
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Affiliation(s)
- Elbert E M Chia
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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20
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Yuan HQ, Singleton J, Balakirev FF, Baily SA, Chen GF, Luo JL, Wang NL. Nearly isotropic superconductivity in (Ba,K)Fe2As2. Nature 2009; 457:565-8. [DOI: 10.1038/nature07676] [Citation(s) in RCA: 444] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2008] [Accepted: 11/24/2008] [Indexed: 11/09/2022]
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21
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Chen GF, Li Z, Li G, Zhou J, Wu D, Dong J, Hu WZ, Zheng P, Chen ZJ, Yuan HQ, Singleton J, Luo JL, Wang NL. Superconducting properties of the Fe-based layered superconductor LaFeAsO0.9F0.1-delta. Phys Rev Lett 2008; 101:057007. [PMID: 18764424 DOI: 10.1103/physrevlett.101.057007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2008] [Indexed: 05/15/2023]
Abstract
We have employed a new route to synthesize single phase F-doped LaOFeAs compound and confirmed the superconductivity above 20 K in this Fe-based system. We show that the new superconductor has a rather high upper critical field of over 50 T. A clear signature of superconducting gap opening below T(c) was observed in the far-infrared reflectance spectra, with 2Delta/kT(c) approximately 3.5-4.2. Furthermore, we show that the new superconductor has electron-type conducting carriers with a rather low-carrier density.
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Affiliation(s)
- G F Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
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22
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Pedrazzini P, Wilhelm H, Jaccard D, Jarlborg T, Schmidt M, Hanfland M, Akselrud L, Yuan HQ, Schwarz U, Grin Y, Steglich F. Metallic state in cubic FeGe beyond its quantum phase transition. Phys Rev Lett 2007; 98:047204. [PMID: 17358807 DOI: 10.1103/physrevlett.98.047204] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Indexed: 05/14/2023]
Abstract
We report on results of electrical resistivity and structural investigations on the cubic modification of FeGe under high pressure. The long-wavelength helical order (T(C) = 280 K) is suppressed at a critical pressure p(c) approximately 19 GPa. An anomaly at T(X)(p) and strong deviations from a Fermi-liquid behavior in a wide pressure range above p(c) suggest that the suppression of T(C) disagrees with the standard notion of a quantum critical phase transition. The metallic ground state persisting at high pressure can be described by band-structure calculations if zero-point motion is included. The shortest FeGe interatomic distance display discontinuous changes in the pressure dependence close to the T(C)(p) phase line.
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Affiliation(s)
- P Pedrazzini
- DPMC, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Genève 4, Switzerland
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23
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Yuan HQ, Agterberg DF, Hayashi N, Badica P, Vandervelde D, Togano K, Sigrist M, Salamon MB. S-wave spin-triplet order in superconductors without inversion symmetry: Li2Pd3B and Li2Pt3B. Phys Rev Lett 2006; 97:017006. [PMID: 16907402 DOI: 10.1103/physrevlett.97.017006] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Indexed: 05/11/2023]
Abstract
We investigate the order parameter of noncentrosymmetric superconductors Li2Pd3B and Li2Pt3B via the behavior of the penetration depth lambda(T). The low-temperature penetration depth shows BCS-like behavior in Li2Pd3B, while in Li2Pt3B it follows a linear temperature dependence. We propose that broken inversion symmetry and the accompanying antisymmetric spin-orbit coupling, which admix spin-singlet and spin-triplet pairing, are responsible for this behavior. The triplet contribution is weak in Li2Pd3B, leading to a wholly open but anisotropic gap. The significantly larger spin-orbit coupling in Li2Pt3B allows the spin-triplet component to be larger in Li2Pt3B, producing line nodes in the energy gap as evidenced by the linear temperature dependence of lambda(T). The experimental data are in quantitative agreement with theory.
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Affiliation(s)
- H Q Yuan
- Department of Physics, University of Illinois at Urbana and Champaign, 1110 West Green Street, Urbana, Illinois 61801, USA.
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24
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Park T, Ronning F, Yuan HQ, Salamon MB, Movshovich R, Sarrao JL, Thompson JD. Hidden magnetism and quantum criticality in the heavy fermion superconductor CeRhIn5. Nature 2006; 440:65-8. [PMID: 16511490 DOI: 10.1038/nature04571] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2005] [Accepted: 01/02/2006] [Indexed: 11/08/2022]
Abstract
With only a few exceptions that are well understood, conventional superconductivity does not coexist with long-range magnetic order (for example, ref. 1). Unconventional superconductivity, on the other hand, develops near a phase boundary separating magnetically ordered and magnetically disordered phases. A maximum in the superconducting transition temperature T(c) develops where this boundary extrapolates to zero Kelvin, suggesting that fluctuations associated with this magnetic quantum-critical point are essential for unconventional superconductivity. Invariably, though, unconventional superconductivity masks the magnetic phase boundary when T < T(c), preventing proof of a magnetic quantum-critical point. Here we report specific-heat measurements of the pressure-tuned unconventional superconductor CeRhIn5 in which we find a line of quantum-phase transitions induced inside the superconducting state by an applied magnetic field. This quantum-critical line separates a phase of coexisting antiferromagnetism and superconductivity from a purely unconventional superconducting phase, and terminates at a quantum tetracritical point where the magnetic field completely suppresses superconductivity. The T --> 0 K magnetic field-pressure phase diagram of CeRhIn5 is well described with a theoretical model developed to explain field-induced magnetism in the high-T(c) copper oxides, but in which a clear delineation of quantum-phase boundaries has not been possible. These experiments establish a common relationship among hidden magnetism, quantum criticality and unconventional superconductivity in copper oxides and heavy-electron systems such as CeRhIn5.
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Affiliation(s)
- Tuson Park
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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25
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Yuan HQ, Grosche FM, Deppe M, Sparn G, Geibel C, Steglich F. Non-Fermi liquid states in the pressurized CeCu2(Si1-xGex)2 system: two critical points. Phys Rev Lett 2006; 96:047008. [PMID: 16486879 DOI: 10.1103/physrevlett.96.047008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Indexed: 05/06/2023]
Abstract
In the archetypal strongly correlated electron superconductor CeCu2Si2 and its Ge-substituted alloys CeCu2(Si1-xGex)2 two quantum phase transitions--one magnetic and one of so far unknown origin-can be crossed as a function of pressure. We examine the associated anomalous normal state by detailed measurements of the low temperature resistivity (rho) power-law exponent alpha. At the lower critical point (at pcl, 1<or=alpha<or=1.5) alpha depends strongly on Ge concentration x and thereby on disorder level, consistent with a Hlubina-Rice-Rosch scenario of critical scattering off antiferromagnetic fluctuations. By contrast, alpha is independent of x at the upper quantum phase transition (at pc2, alpha approximately equal to 1), suggesting critical scattering from local or q=0 modes, in agreement with a density- or valence-fluctuation approach.
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Affiliation(s)
- H Q Yuan
- Max-Planck-Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany.
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26
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Abstract
We report the presence of two disconnected superconducting domes in the pressure-temperature phase diagram of partially germanium-substituted CeCu2Si2. The lower density superconducting dome lies on the threshold of antiferromagnetic order, indicating magnetically mediated pairing, whereas the higher density superconducting regime straddles a weakly first-order volume collapse, suggesting a pairing interaction based on spatially extended density fluctuations. Two distinct pairing mechanisms thus appear to operate in the single, wide, superconducting range of stoichiometric CeCu2Si2, both of which might apply more generally to other classes of correlated electron systems.
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Affiliation(s)
- H Q Yuan
- Max-Planck-Institute for Chemical Physics of Solids, Nöthnitzer Strabetae 40, 01187 Dresden, Germany.
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27
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Grosche FM, Yuan HQ, Carrillo-Cabrera W, Paschen S, Langhammer C, Kromer F, Sparn G, Baenitz M, Grin Y, Steglich F. Superconductivity in the filled cage compounds Ba6Ge25 and Ba4Na2Ge25. Phys Rev Lett 2001; 87:247003. [PMID: 11736532 DOI: 10.1103/physrevlett.87.247003] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2001] [Indexed: 05/23/2023]
Abstract
The clathrate compound Ba 6Ge25 and its relatives consist of a rigid germanium skeleton, into which barium or other metal atoms are coordinated. These guest atoms can "rattle" freely at high temperatures, but in Ba 6Ge25 some of them lock randomly into split positions below T(S) approximately 200 K. The resulting bad metal undergoes a BCS-like superconducting transition at T(c) approximately 0.24 K. T(c) increases more than 16-fold, as T(S) is suppressed by hydrostatic pressure p, but changes only slightly with p from T(c) approximately 0.84 K in the undistorted sister compound Ba 4Na2Ge25. The large enhancement of T(c) in Ba 6Ge25 may be attributed mainly to the pressure tuning of strong disorder caused by the random displacement of Ba atoms at T(S).
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Affiliation(s)
- F M Grosche
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, D-01187 Dresden, Germany
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Yuan HQ, Zuo CX. [Chemical constituents of Cynanchum thesioides K. Schum]. Zhongguo Zhong Yao Za Zhi 1992; 17:739-41, 763. [PMID: 1304755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- H Q Yuan
- Institute of Materia Medica, Shandong Academy of Medical Sciences, Jinan
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