1
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Wang S, Yu Y, Hao J, Liang K, Xiang B, Zhu J, Lin Y, Pan Y, Gu G, Watanabe K, Taniguchi T, Qi Y, Zhang Y, Wang Y. Oscillating paramagnetic Meissner effect and Berezinskii-Kosterlitz-Thouless transition in underdoped Bi 2Sr 2CaCu 2O 8+δ. Natl Sci Rev 2024; 11:nwad249. [PMID: 38577674 PMCID: PMC10989300 DOI: 10.1093/nsr/nwad249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 07/01/2023] [Accepted: 08/31/2023] [Indexed: 04/06/2024] Open
Abstract
Superconducting phase transitions in two dimensions lie beyond the description of the Ginzburg-Landau symmetry-breaking paradigm for three-dimensional superconductors. They are Berezinskii-Kosterlitz-Thouless (BKT) transitions of paired-electron condensate driven by the unbinding of topological excitations, i.e. vortices. The recently discovered monolayers of layered high-transition-temperature ([Formula: see text]) cuprate superconductor Bi2Sr2CaCu2O8+δ (Bi2212) meant that this 2D superconductor promised to be ideal for the study of unconventional superconductivity. But inhomogeneity posed challenges for distinguishing BKT physics from charge correlations in this material. Here, we utilize the phase sensitivity of scanning superconducting quantum interference device microscopy susceptometry to image the local magnetic response of underdoped Bi2212 from the monolayer to the bulk throughout its phase transition. The monolayer segregates into domains with independent phases at elevated temperatures below [Formula: see text]. Within a single domain, we find that the susceptibility oscillates with flux between diamagnetism and paramagnetism in a Fraunhofer-like pattern up to [Formula: see text]. The finite modulation period, as well as the broadening of the peaks when approaching [Formula: see text] from below, suggests well-defined vortices that are increasingly screened by the dissociation of vortex-antivortex plasma through a BKT transition. In the multilayers, the susceptibility oscillation differs in a small temperature regime below [Formula: see text], consistent with a dimensional crossover led by interlayer coupling. Serving as strong evidence for BKT transition in the bulk, we observe a sharp jump in phase stiffness and paramagnetism at small fields just below [Formula: see text]. These results unify the superconducting phase transitions from the monolayer to the bulk underdoped Bi2212, and can be collectively referred to as the BKT transition with interlayer coupling.
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Affiliation(s)
- Shiyuan Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yijun Yu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Jinxiang Hao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Keyi Liang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Bingke Xiang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Jinjiang Zhu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yishi Lin
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yinping Pan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Genda Gu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044, Japan
| | - Yang Qi
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yuanbo Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Yihua Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
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2
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Tazai R, Yamakawa Y, Kontani H. Drastic magnetic-field-induced chiral current order and emergent current-bond-field interplay in kagome metals. Proc Natl Acad Sci U S A 2024; 121:e2303476121. [PMID: 38207076 PMCID: PMC10801867 DOI: 10.1073/pnas.2303476121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 11/22/2023] [Indexed: 01/13/2024] Open
Abstract
In kagome metals, the chiral current order parameter [Formula: see text] with time-reversal-symmetry-breaking is the source of various exotic electronic states, while the method of controlling the current order and its interplay with the star-of-David bond order [Formula: see text] are still unsolved. Here, we reveal that tiny uniform orbital magnetization [Formula: see text] is induced by the chiral current order, and its magnitude is prominently enlarged under the presence of the bond order. Importantly, we derive the magnetic-field ([Formula: see text])-induced Ginzburg-Landau (GL) free energy expression [Formula: see text], which enables us to elucidate the field-induced current-bond phase transitions in kagome metals. The emergent current-bond-[Formula: see text] trilinear coupling term in the free energy, [Formula: see text], naturally explains the characteristic magnetic-field sensitive electronic states in kagome metals, such as the field-induced current order and the strong interplay between the bond and current orders. The GL coefficients of [Formula: see text] derived from the realistic multiorbital model are appropriate to explain various experiments. Furthermore, we discuss the field-induced loop current orders in the square lattice models that have been studied in cuprate superconductors.
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Affiliation(s)
- Rina Tazai
- Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto606-8502, Japan
| | | | - Hiroshi Kontani
- Department of Physics, Nagoya University, Nagoya464-8602, Japan
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3
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Tazai R, Yamakawa Y, Kontani H. Charge-loop current order and Z 3 nematicity mediated by bond order fluctuations in kagome metals. Nat Commun 2023; 14:7845. [PMID: 38030600 PMCID: PMC10687221 DOI: 10.1038/s41467-023-42952-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 10/25/2023] [Indexed: 12/01/2023] Open
Abstract
Recent experiments on geometrically frustrated kagome metal AV3Sb5 (A = K, Rb, Cs) have revealed the emergence of the charge loop current (cLC) order near the bond order (BO) phase. However, the origin of the cLC and its interplay with other phases have been uncovered. Here, we propose a novel mechanism of the cLC state, by focusing on the BO phase common in kagome metals. The BO fluctuations in kagome metals, which emerges due to the Coulomb interaction and the electron-phonon coupling, mediate the odd-parity particle-hole condensation that gives rise to the topological current order. Furthermore, the predicted cLC+BO phase gives rise to the Z3-nematic state in addition to the giant anomalous Hall effect. The present theory predicts the close relationship between the cLC, the BO, and the nematicity, which is significant to understand the cascade of quantum electron states in kagome metals. The present scenario provides a natural understanding.
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Grants
- JP20K22328 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- JP22K14003 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- JP19H05825 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- JP20K03858 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
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Affiliation(s)
- Rina Tazai
- Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, 606-8502, Japan.
| | - Youichi Yamakawa
- Department of Physics, Nagoya University, Furo-cho, Nagoya, 464-8602, Japan
| | - Hiroshi Kontani
- Department of Physics, Nagoya University, Furo-cho, Nagoya, 464-8602, Japan
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4
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Wen C, Qin T, Zhang X, Zhang M, Hu W, Shen S, Yang Z, Qi Y, Li G, Yan S. Probing Hidden Mott Gap and Incommensurate Charge Modulation on the Polar Surfaces of PdCrO_{2}. PHYSICAL REVIEW LETTERS 2023; 131:116501. [PMID: 37774284 DOI: 10.1103/physrevlett.131.116501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 06/07/2023] [Accepted: 08/23/2023] [Indexed: 10/01/2023]
Abstract
Here we report a combined study of low-temperature scanning tunneling microscopy and dynamical mean-field theory on PdCrO_{2}, a delafossite metal with an antiferromagnetic order below ∼37.5 K. First, on the CrO_{2}-terminated polar surface we detect a gaplike feature both below and above the Néel temperature. The dynamical mean-field theory calculations indicate that this gap is opened due to the strong correlations of Cr-3d electrons, suggesting the hidden Mott nature of the gap. Then, we observe two kinds of Pd-terminated polar surfaces. One is a well-ordered Pd surface with the Fermi-surface-nesting-induced incommensurate charge modulation, while the other one is a reconstructed Pd surface with the individual nanoscale nonperiodic domain structures. On the well-ordered Pd surface, the interference between the incommensurate charge modulation and the atomic lattice forms the periodic moiré pattern. Our results provide important microscopic information for fully understanding the correlated electronic properties of this class of materials.
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Affiliation(s)
- Chenhaoping Wen
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Tian Qin
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xuefeng Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Mingxin Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Weixiong Hu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Shiwei Shen
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Zhongzheng Yang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yanpeng Qi
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China
- Shanghai Key Laboratory of High-resolution Electron Microscopy, ShanghaiTech University, Shanghai 201210, China
| | - Gang Li
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China
| | - Shichao Yan
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China
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5
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Kang M, Zhang CC, Schierle E, McCoy S, Li J, Sutarto R, Suter A, Prokscha T, Salman Z, Weschke E, Cybart S, Wei JYT, Comin R. Discovery of charge order in a cuprate Mott insulator. Proc Natl Acad Sci U S A 2023; 120:e2302099120. [PMID: 37459539 PMCID: PMC10372577 DOI: 10.1073/pnas.2302099120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 06/12/2023] [Indexed: 07/29/2023] Open
Abstract
Copper oxide superconductors universally exhibit multiple forms of electronically ordered phases that break the native translational symmetry of the CuO2 planes. In underdoped cuprates with correlated metallic ground states, charge/spin stripes and incommensurate charge density waves (CDWs) have been experimentally observed over the years, while early theoretical studies also predicted the emergence of a Coulomb-frustrated 'charge crystal' phase in the very lightly doped, insulating limit of CuO2 planes. Here, we search for signatures of CDW order in very lightly hole-doped cuprates from the 123 family RBa2Cu3O7 - δ (RBCO; R: Y or rare earth), by using resonant X-ray scattering, electron transport, and muon spin rotation measurements to resolve the electronic and magnetic ground states fully. Specifically, Pr is used to substitute Y at the R-site to systematically suppress the superconductivity and access the extremely low hole-doping regime of the cuprate phase diagram without changing the oxygen stoichiometry. X-ray scattering data taken on Pr-doped YBCO thin films reveal an in-plane CDW order that follows the same linear evolution of wave vector versus hole concentration as oxygen-underdoped YBCO but extends all the way to the insulating and magnetically ordered Mott limit. Combined with the recent observation of charge crystal phase on an insulating surface of Bi2Sr2CaCu2O8 + z, our results in RBCO suggest that this electronic symmetry breaking is universally present in very lightly doped CuO2 planes. These findings bridge the gap between the Mott insulating state and the underdoped metallic state and underscore the prominent role that Coulomb-frustrated electronic phase separation plays among all cuprates.
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Affiliation(s)
- Mingu Kang
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA02139
- Center for Complex Phase of Materials, Max Planck POSTECH/Korea Research Initiative, Pohang790-884, Republic of Korea
| | - Chao C. Zhang
- Department of Physics, University of Toronto, Toronto, ONM5S1A7, Canada
| | - Enrico Schierle
- Helmholtz-Zentrum Berlin für Materialien und Energie, BerlinD-12489, Germany
| | - Stephen McCoy
- Department of Materials Science and Engineering, University of California, Riverside, CA92521
- Department of Electrical Engineering, University of California, Riverside, CA92521
| | - Jiarui Li
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA02139
| | | | - Andreas Suter
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, VilligenCH-5232, Switzerland
| | - Thomas Prokscha
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, VilligenCH-5232, Switzerland
| | - Zaher Salman
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, VilligenCH-5232, Switzerland
| | - Eugene Weschke
- Helmholtz-Zentrum Berlin für Materialien und Energie, BerlinD-12489, Germany
| | - Shane Cybart
- Department of Materials Science and Engineering, University of California, Riverside, CA92521
- Department of Electrical Engineering, University of California, Riverside, CA92521
| | - John Y. T. Wei
- Department of Physics, University of Toronto, Toronto, ONM5S1A7, Canada
| | - Riccardo Comin
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA02139
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6
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Wang Y, Su T, Cui Y, Ma X, Zhou X, Wang Y, Hu S, Ren W. Cuprate superconducting materials above liquid nitrogen temperature from machine learning. RSC Adv 2023; 13:19836-19845. [PMID: 37404317 PMCID: PMC10315706 DOI: 10.1039/d3ra02848h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 06/08/2023] [Indexed: 07/06/2023] Open
Abstract
The superconductivity of cuprates remains a challenging topic in condensed matter physics, and the search for materials that superconduct electricity above liquid nitrogen temperature and even at room temperature is of great significance for future applications. Nowadays, with the advent of artificial intelligence, research approaches based on data science have achieved excellent results in material exploration. We investigated machine learning (ML) models by employing separately the element symbolic descriptor atomic feature set 1 (AFS-1) and a prior physics knowledge descriptor atomic feature set 2 (AFS-2). An analysis of the manifold in the hidden layer of the deep neural network (DNN) showed that cuprates still offer the greatest potential as superconducting candidates. By calculating the SHapley Additive exPlanations (SHAP) value, it is evident that the covalent bond length and hole doping concentration emerge as the crucial factors influencing the superconducting critical temperature (Tc). These findings align with our current understanding of the subject, emphasizing the significance of these specific physical quantities. In order to improve the robustness and practicability of our model, two types of descriptors were used to train the DNN. We also proposed the idea of cost-sensitive learning, predicted the sample in another dataset, and designed a virtual high-throughput search workflow.
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Affiliation(s)
- Yuxue Wang
- Department of Physics, Material Genome Institute, Institute for the Conservation of Cultural Heritage, Shanghai University Shanghai 200444 China
- Shanghai Key Laboratory of High Temperature Superconductors, International Center for Quantum and Molecular Structures, Shanghai University Shanghai 200444 China
- Zhejiang Lab Hangzhou 311100 China
| | - Tianhao Su
- Department of Physics, Material Genome Institute, Institute for the Conservation of Cultural Heritage, Shanghai University Shanghai 200444 China
- Shanghai Key Laboratory of High Temperature Superconductors, International Center for Quantum and Molecular Structures, Shanghai University Shanghai 200444 China
- Zhejiang Lab Hangzhou 311100 China
| | - Yaning Cui
- Department of Physics, Material Genome Institute, Institute for the Conservation of Cultural Heritage, Shanghai University Shanghai 200444 China
- Shanghai Key Laboratory of High Temperature Superconductors, International Center for Quantum and Molecular Structures, Shanghai University Shanghai 200444 China
- Zhejiang Lab Hangzhou 311100 China
| | - Xianzhe Ma
- Department of Physics, Material Genome Institute, Institute for the Conservation of Cultural Heritage, Shanghai University Shanghai 200444 China
- Shanghai Key Laboratory of High Temperature Superconductors, International Center for Quantum and Molecular Structures, Shanghai University Shanghai 200444 China
- Zhejiang Lab Hangzhou 311100 China
| | - Xue Zhou
- Center for Spintronics and Quantum Systems, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University Xi'an Shaanxi 710049 China
| | - Yin Wang
- Department of Physics, Material Genome Institute, Institute for the Conservation of Cultural Heritage, Shanghai University Shanghai 200444 China
- Shanghai Key Laboratory of High Temperature Superconductors, International Center for Quantum and Molecular Structures, Shanghai University Shanghai 200444 China
- Zhejiang Lab Hangzhou 311100 China
| | - Shunbo Hu
- Department of Physics, Material Genome Institute, Institute for the Conservation of Cultural Heritage, Shanghai University Shanghai 200444 China
- Shanghai Key Laboratory of High Temperature Superconductors, International Center for Quantum and Molecular Structures, Shanghai University Shanghai 200444 China
- Zhejiang Lab Hangzhou 311100 China
| | - Wei Ren
- Department of Physics, Material Genome Institute, Institute for the Conservation of Cultural Heritage, Shanghai University Shanghai 200444 China
- Shanghai Key Laboratory of High Temperature Superconductors, International Center for Quantum and Molecular Structures, Shanghai University Shanghai 200444 China
- Zhejiang Lab Hangzhou 311100 China
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7
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Qin T, Zhong R, Cao W, Shen S, Wen C, Qi Y, Yan S. Real-Space Observation of Unidirectional Charge Density Wave and Complex Structural Modulation in the Pnictide Superconductor Ba 1-xSr xNi 2As 2. NANO LETTERS 2023; 23:2958-2963. [PMID: 37011415 DOI: 10.1021/acs.nanolett.3c00323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Here we use low-temperature and variable-temperature scanning tunneling microscopy to study the pnictide superconductor, Ba1-xSrxNi2As2. In the low-temperature phase (triclinic phase) of BaNi2As2, we observe the unidirectional charge density wave (CDW) with Q = 1/3 on both the Ba and NiAs surfaces. On the NiAs surface of the triclinic BaNi2As2, there are structural-modulation-induced chain-like superstructures with distinct periodicities. In the high-temperature phase (tetragonal phase) of BaNi2As2, the NiAs surface appears as the periodic 1 × 2 superstructure. Interestingly, in the triclinic phase of Ba0.5Sr0.5Ni2As2, the unidirectional CDW is suppressed on both the Ba/Sr and NiAs surfaces, and the Sr substitution stabilizes the periodic 1 × 2 superstructure on the NiAs surface, which enhance the superconductivity in Ba0.5Sr0.5Ni2As2. Our results provide important microscopic insights for the interplay among the unidirectional CDW, structural modulation, and superconductivity in this class of pnictide superconductors.
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Affiliation(s)
- Tian Qin
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ruixia Zhong
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Weizheng Cao
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Shiwei Shen
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Chenhaoping Wen
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yanpeng Qi
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China
- Shanghai Key Laboratory of High-Resolution Electron Microscopy, ShanghaiTech University, Shanghai 201210, China
| | - Shichao Yan
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China
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8
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Ru H, Li Z, Wang S, Xiang B, Wang Y. Suppression and Revival of Superconducting Phase Coherence in Monolayer FeSe/SrTiO 3. NANO LETTERS 2022; 22:9997-10002. [PMID: 36519788 DOI: 10.1021/acs.nanolett.2c03587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Monolayer FeSe grown on SrTiO3 (FeSe/STO) is an interfacial high-temperature superconductor distinctively different from bulk FeSe. However, the superconducting phase coherence of the interface is challenging to probe due to its fragility in the atmosphere. Here, we perform in situ mutual inductance under ultrahigh vacuum on FeSe/STO in combination with band mapping by angle-resolved photoemission spectroscopy. We find that even though the monolayer shows a gap-closing temperature above 50 K, no diamagnetism is visible down to 5 K. This is the case for few-layer FeSe/STO until it exceeds a critical number of five layers, where diamagnetism suddenly appears. The suppression of diamagnetism in the monolayer is also lifted by depositing a top FeTe layer. However, Tc and superfluid density both decrease with thicker FeTe, suggesting unconventional electron pairing and phase coherence competition. Our observation may be understood by a scenario in which the interfacial superconducting phase coherence is highly anisotropic.
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Affiliation(s)
- Hao Ru
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
| | - Zhijie Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
| | - Shiyuan Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
| | - Bingke Xiang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
| | - Yihua Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, People's Republic of China
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9
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Xue H, Wang L, Wang Z, Zhang G, Peng W, Wu S, Gao CL, An Z, Chen Y, Li W. Fourfold Symmetric Superconductivity in Spinel Oxide LiTi 2O 4(001) Thin Films. ACS NANO 2022; 16:19464-19471. [PMID: 36331279 DOI: 10.1021/acsnano.2c09338] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The charge frustration with the mixed-valence state inherent to LiTi2O4, which is found to be the only oxide superconductor with spinel structure, is the impetus for paying special attention to unveil the underlying intriguing superconducting properties. Here, we report a pronounced fourfold rotational symmetry of the superconductivity in high-quality single-crystalline LiTi2O4(001) thin films. Both the magnetoresistivity and upper critical field under an applied magnetic field manifest striking fourfold oscillations deep inside the superconducting state, whereas the anisotropy vanishes in the normal state, demonstrating that it is an intrinsic property of the superconducting phase. We attribute this behavior to the unconventional d-wave superconducting Cooper pairs with the irreducible representation of Eg protected by the Oh point group in cubic LiTi2O4. Our findings show the nontrivial character of the pairing interaction in a three-dimensional spinel oxide superconductor.
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Affiliation(s)
| | | | | | | | - Wei Peng
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, and Center for Excellence in Superconducting Electronics, Chinese Academy of Sciences, Shanghai 200050, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
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10
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Wandel S, Boschini F, da Silva Neto EH, Shen L, Na MX, Zohar S, Wang Y, Welch SB, Seaberg MH, Koralek JD, Dakovski GL, Hettel W, Lin MF, Moeller SP, Schlotter WF, Reid AH, Minitti MP, Boyle T, He F, Sutarto R, Liang R, Bonn D, Hardy W, Kaindl RA, Hawthorn DG, Lee JS, Kemper AF, Damascelli A, Giannetti C, Turner JJ, Coslovich G. Enhanced charge density wave coherence in a light-quenched, high-temperature superconductor. Science 2022; 376:860-864. [PMID: 35587968 DOI: 10.1126/science.abd7213] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Superconductivity and charge density waves (CDWs) are competitive, yet coexisting, orders in cuprate superconductors. To understand their microscopic interdependence, a probe capable of discerning their interaction on its natural length and time scale is necessary. We use ultrafast resonant soft x-ray scattering to track the transient evolution of CDW correlations in YBa2Cu3O6+x after the quench of superconductivity by an infrared laser pulse. We observe a nonthermal response of the CDW order characterized by a near doubling of the correlation length within ≈1 picosecond of the superconducting quench. Our results are consistent with a model in which the interaction between superconductivity and CDWs manifests inhomogeneously through disruption of spatial coherence, with superconductivity playing the dominant role in stabilizing CDW topological defects, such as discommensurations.
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Affiliation(s)
- S Wandel
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - F Boschini
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada.,Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.,Centre Énergie Matériaux Télécommunications, Institut National de la Recherche Scientifique, Varennes, QC J3X 1S2, Canada
| | - E H da Silva Neto
- Department of Physics, Yale University, New Haven, CT 06520, USA.,Energy Sciences Institute, Yale University, New Haven, CT 06516, USA.,Department of Physics, University of California, Davis, CA 95616, USA
| | - L Shen
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA
| | - M X Na
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada.,Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - S Zohar
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Y Wang
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - S B Welch
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - M H Seaberg
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - J D Koralek
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - G L Dakovski
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - W Hettel
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - M-F Lin
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - S P Moeller
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - W F Schlotter
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - A H Reid
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - M P Minitti
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - T Boyle
- Department of Physics, Yale University, New Haven, CT 06520, USA.,Energy Sciences Institute, Yale University, New Haven, CT 06516, USA.,Department of Physics, University of California, Davis, CA 95616, USA
| | - F He
- Canadian Light Source, Saskatoon, SK S7N 2V3, Canada
| | - R Sutarto
- Canadian Light Source, Saskatoon, SK S7N 2V3, Canada
| | - R Liang
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada.,Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - D Bonn
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada.,Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - W Hardy
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada.,Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - R A Kaindl
- Department of Physics, Arizona State University, Tempe, AZ 85287, USA.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - D G Hawthorn
- Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - J-S Lee
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - A F Kemper
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - A Damascelli
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada.,Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - C Giannetti
- Department of Mathematics and Physics, Università Cattolica del Sacro Cuore, Brescia, BS I-25121, Italy
| | - J J Turner
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA
| | - G Coslovich
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
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11
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Tazai R, Yamakawa Y, Onari S, Kontani H. Mechanism of exotic density-wave and beyond-Migdal unconventional superconductivity in kagome metal AV 3Sb 5 (A = K, Rb, Cs). SCIENCE ADVANCES 2022; 8:eabl4108. [PMID: 35363527 PMCID: PMC10938589 DOI: 10.1126/sciadv.abl4108] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 02/09/2022] [Indexed: 05/12/2023]
Abstract
Exotic quantum phase transitions in metals, such as the electronic nematic state, have been discovered one after another and found to be universal now. The emergence of unconventional density-wave (DW) order in frustrated kagome metal AV3Sb5 and its interplay with exotic superconductivity attract increasing attention. We find that the DW in kagome metal is the bond order, because the sizable intersite attraction is caused by the quantum interference among paramagnons. This mechanism is important in kagome metals because the geometrical frustration prohibits the freezing of paramagnons. In addition, we uncover that moderate bond-order fluctuations mediate sizable pairing glue, and this mechanism gives rise to both singlet s-wave and triplet p-wave superconductivity. Furthermore, characteristic pressure-induced phase transitions in CsV3Cb5 are naturally understood by the present theory. Thus, both the exotic density wave and the superconductivity in geometrically frustrated kagome metals are explained by the quantum interference mechanism.
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12
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Onari S, Kontani H. SU(4) Valley+Spin Fluctuation Interference Mechanism for Nematic Order in Magic-Angle Twisted Bilayer Graphene: The Impact of Vertex Corrections. PHYSICAL REVIEW LETTERS 2022; 128:066401. [PMID: 35213199 DOI: 10.1103/physrevlett.128.066401] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 08/10/2021] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
In the magic-angle twisted bilayer graphene (MATBG), one of the most remarkable observations is the C_{3}-symmetry-breaking nematic state. We identify that the nematicity in MATBG is the E-symmetry ferro bond order, which is the modulation of correlated hopping integrals owing to the E-symmetry particle-hole pairing condensation. The nematicity in MATBG originates from prominent quantum interference among SU(4) valley+spin composite fluctuations. This novel "valley+spin fluctuation interference mechanism" is revealed by the density wave equation analysis for the realistic multiorbital Hubbard model for MATBG. We find that the nematic state is robust once three van Hove singularity points exist in each valley. This interference mechanism also causes novel time-reversal-symmetry-broken valley polarization accompanied by a charge loop current. We discuss interesting similarities and differences between MATBG and Fe-based superconductors.
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Affiliation(s)
- Seiichiro Onari
- Department of Physics, Nagoya University, Furo-cho, Nagoya 464-8602, Japan
| | - Hiroshi Kontani
- Department of Physics, Nagoya University, Furo-cho, Nagoya 464-8602, Japan
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13
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Cai X, Li ZX, Yao H. Antiferromagnetism Induced by Bond Su-Schrieffer-Heeger Electron-Phonon Coupling: A Quantum Monte Carlo Study. PHYSICAL REVIEW LETTERS 2021; 127:247203. [PMID: 34951814 DOI: 10.1103/physrevlett.127.247203] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/22/2021] [Accepted: 10/28/2021] [Indexed: 06/14/2023]
Abstract
Antiferromagnetism (AFM) such as Néel ordering is often closely related to Coulomb interactions such as Hubbard repulsion in two-dimensional (2D) systems. Whether Néel AFM ordering in two dimensions can be dominantly induced by electron-phonon couplings (EPC) has not been completely understood. Here, by employing numerically exact sign-problem-free quantum Monte Carlo (QMC) simulations, we show that bond Su-Schrieffer-Heeger (SSH) phonons with frequency ω and EPC constant λ can induce AFM ordering for a wide range of phonon frequency ω>ω_{c}. For ω<ω_{c}, a valence-bond-solid (VBS) order appears and there is a direct quantum phase transition between VBS and AFM phases at ω_{c}. The phonon mechanism of the AFM ordering is related to the fact that SSH phonons directly couple to electron hopping whose second-order process can induce an effective AFM spin exchange. Our results shall shed new light on understanding AFM ordering in correlated quantum materials.
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Affiliation(s)
- Xun Cai
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
| | - Zi-Xiang Li
- Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Hong Yao
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
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14
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Wang Y, Chen Z, Shi T, Moritz B, Shen ZX, Devereaux TP. Phonon-Mediated Long-Range Attractive Interaction in One-Dimensional Cuprates. PHYSICAL REVIEW LETTERS 2021; 127:197003. [PMID: 34797146 DOI: 10.1103/physrevlett.127.197003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 09/22/2021] [Indexed: 06/13/2023]
Abstract
Establishing a minimal microscopic model for cuprates is a key step towards the elucidation of a high-T_{c} mechanism. By a quantitative comparison with a recent in situ angle-resolved photoemission spectroscopy measurement in doped 1D cuprate chains, our simulation identifies a crucial contribution from long-range electron-phonon coupling beyond standard Hubbard models. Using reasonable ranges of coupling strengths and phonon energies, we obtain a strong attractive interaction between neighboring electrons, whose strength is comparable to experimental observations. Nonlocal couplings play a significant role in the mediation of neighboring interactions. Considering the structural and chemical similarity between 1D and 2D cuprate materials, this minimal model with long-range electron-phonon coupling will provide important new insights on cuprate high-T_{c} superconductivity and related quantum phases.
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Affiliation(s)
- Yao Wang
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29631, USA
| | - Zhuoyu Chen
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Departments of Physics and Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Tao Shi
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Brian Moritz
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Zhi-Xun Shen
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Departments of Physics and Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Thomas P Devereaux
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
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15
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Choi J, Zadorozhko AA, Choi J, Kim E. Spatially Modulated Superfluid State in Two-Dimensional ^{4}He Films. PHYSICAL REVIEW LETTERS 2021; 127:135301. [PMID: 34623862 DOI: 10.1103/physrevlett.127.135301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 07/30/2021] [Indexed: 06/13/2023]
Abstract
The second layer of ^{4}He films adsorbed on a graphite substrate is an excellent experimental platform to study the interplay between superfluid and structural orders. Here, we report a rigid two-frequency torsional oscillator study on the second layer as a function of temperature and ^{4}He atomic density. For the first time, we show experimentally that the superfluid density is independent of frequency, which can be interpreted as unequivocal evidence of genuine superfluidity. The phase diagram established in this work reveals that a superfluid phase coexists with hexatic density-wave correlation and a registered solid phase. This suggests the second layer as a candidate for hosting two exotic quantum ground states: the spatially modulated superfluid and supersolid phases resulting from the interplay between superfluid and structural orders.
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Affiliation(s)
- Jaewon Choi
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Alexey A Zadorozhko
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Jeakyung Choi
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Eunseong Kim
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
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16
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Chen KY, Wang NN, Yin QW, Gu YH, Jiang K, Tu ZJ, Gong CS, Uwatoko Y, Sun JP, Lei HC, Hu JP, Cheng JG. Double Superconducting Dome and Triple Enhancement of T_{c} in the Kagome Superconductor CsV_{3}Sb_{5} under High Pressure. PHYSICAL REVIEW LETTERS 2021; 126:247001. [PMID: 34213920 DOI: 10.1103/physrevlett.126.247001] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 05/18/2021] [Indexed: 05/12/2023]
Abstract
CsV_{3}Sb_{5} is a newly discovered Z_{2} topological kagome metal showing the coexistence of a charge-density-wave (CDW)-like order at T^{*}=94 K and superconductivity (SC) at T_{c}=2.5 K at ambient pressure. Here, we study the interplay between CDW and SC in CsV_{3}Sb_{5} via measurements of resistivity, dc and ac magnetic susceptibility under various pressures up to 6.6 GPa. We find that the CDW transition decreases with pressure and experience a subtle modification at P_{c1}≈0.6-0.9 GPa before it vanishes completely at P_{c2}≈2 GPa. Correspondingly, T_{c}(P) displays an unusual M-shaped double dome with two maxima around P_{c1} and P_{c2}, respectively, leading to a tripled enhancement of T_{c} to about 8 K at 2 GPa. The obtained temperature-pressure phase diagram resembles those of unconventional superconductors, illustrating an intimated competition between CDW-like order and SC. The competition is found to be particularly strong for the intermediate pressure range P_{c1}≤P≤P_{c2} as evidenced by the broad superconducting transition and reduced superconducting volume fraction. The modification of CDW order around P_{c1} has been discussed based on the band structure calculations. This work not only demonstrates the potential to raise T_{c} of the V-based kagome superconductors, but also offers more insights into the rich physics related to the electron correlations in this novel family of topological kagome metals.
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Affiliation(s)
- K Y Chen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - N N Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Q W Yin
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
| | - Y H Gu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - K Jiang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Z J Tu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
| | - C S Gong
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
| | - Y Uwatoko
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - J P Sun
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - H C Lei
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
| | - J P Hu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - J-G Cheng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
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17
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Jiang D, Pan Y, Wang S, Lin Y, Holland CM, Kirtley JR, Chen X, Zhao J, Chen L, Yin S, Wang Y. Observation of robust edge superconductivity in Fe(Se,Te) under strong magnetic perturbation. Sci Bull (Beijing) 2021; 66:425-432. [PMID: 36654179 DOI: 10.1016/j.scib.2020.10.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/04/2020] [Accepted: 09/29/2020] [Indexed: 01/20/2023]
Abstract
The iron-chalcogenide high temperature superconductor Fe(Se,Te) (FST) has been reported to exhibit complex magnetic ordering and nontrivial band topology which may lead to novel superconducting phenomena. However, the recent studies have so far been largely concentrated on its band and spin structures while its mesoscopic electronic and magnetic response, crucial for future device applications, has not been explored experimentally. Here, we used scanning superconducting quantum interference device microscopy for its sensitivity to both local diamagnetic susceptibility and current distribution in order to image the superfluid density and supercurrent in FST. We found that in FST with 10% interstitial Fe, whose magnetic structure was heavily disrupted, bulk superconductivity was significantly suppressed whereas edge still preserved strong superconducting diamagnetism. The edge dominantly carried supercurrent despite of a very long magnetic penetration depth. The temperature dependences of the superfluid density and supercurrent distribution were distinctively different between the edge and the bulk. Our Heisenberg modeling showed that magnetic dopants stabilize anti-ferromagnetic spin correlation along the edge, which may contribute towards its robust superconductivity. Our observations hold implication for FST as potential platforms for topological quantum computation and superconducting spintronics.
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Affiliation(s)
- Da Jiang
- Shanghai Institute of Microsystem and Information Technology, Shanghai 200050, China.
| | - Yinping Pan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Shiyuan Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yishi Lin
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Connor M Holland
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - John R Kirtley
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Xianhui Chen
- Department of Physics, University of Science and Technology of China, Hefei 230026, China
| | - Jun Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Lei Chen
- Shanghai Institute of Microsystem and Information Technology, Shanghai 200050, China
| | - Shaoyu Yin
- Institute for Theoretical Physics and Cosmology, Zhejiang University of Technology, Hangzhou 310023, China; State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
| | - Yihua Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China.
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18
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Jiang D, Yuan T, Wu Y, Wei X, Mu G, An Z, Li W. Strong In-Plane Magnetic Field-Induced Reemergent Superconductivity in the van der Waals Heterointerface of NbSe 2 and CrCl 3. ACS APPLIED MATERIALS & INTERFACES 2020; 12:49252-49257. [PMID: 33058667 DOI: 10.1021/acsami.0c15203] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A magnetic field is generally considered to be incompatible with superconductivity as it tends to spin-polarize electrons and breaks apart the opposite-spin singlet superconducting Cooper pairs. Here, an experimental phenomenon is observed that an intriguing reemergent superconductivity evolves from a conventional superconductivity undergoing a hump-like intermediate phase with a finite electric resistance in the van der Waals heterointerface of layered NbSe2 and CrCl3 flakes. This phenomenon merely occurred when the applied magnetic field is parallel to the sample plane and perpendicular to the electric current direction as compared to the reference sample of a NbSe2 thin flake. The strong anisotropy of the reemergent superconducting phase is pointed to the nature of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state driven by the strong interfacial spin-orbit coupling between NbSe2 and CrCl3 layers. The theoretical picture of FFLO state nodes induced by Josephson vortices collectively pinning is presented for well understanding the experimental observation of the reemergent superconductivity. This finding sheds light on an opportunity to search for the exotic FFLO state in the van der Waals heterostructures with strong interfacial spin-orbit coupling.
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Affiliation(s)
- Da Jiang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, and Center for Excellence in Superconducting Electronics, Chinese Academy of Science, Shanghai 200050, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tianzhong Yuan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
| | - Yongzheng Wu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
| | - Xinyuan Wei
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
| | - Gang Mu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, and Center for Excellence in Superconducting Electronics, Chinese Academy of Science, Shanghai 200050, People's Republic of China
| | - Zhenghua An
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Wei Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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19
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Rasche B, Yang M, Nikonow L, Cooper JFK, Murray CA, Day SJ, Kleiner K, Clarke SJ, Compton RG. In-situ Electrochemical X-ray Diffraction: A Rigorous Method to Navigate within Phase Diagrams Reveals β-Fe 1+x Se as Superconductor for All x. Angew Chem Int Ed Engl 2019; 58:15401-15406. [PMID: 31433102 DOI: 10.1002/anie.201907426] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 08/09/2019] [Indexed: 11/11/2022]
Abstract
We report the precise postsynthetic control of the composition of β-Fe1+x Se by electrochemistry with simultaneous tracking of the associated structural changes via in situ synchrotron X-ray diffraction. We access the full phase width of 0.01<x<0.04 and identify the superconducting state below 8 K, which in contrast to earlier reports is independent of the composition. However, in a second set of in situ X-ray diffraction experiments, we demonstrate that β-Fe1+x Se forms a new phase in the presence of oxygen above a 100 °C which has the same anti-PbO type structure but is not superconducting down to 1.8 K. The latter process can be reversed electrochemically to reinstate the superconducting state. These observations exploit the exquisite control afforded by electrochemistry in contrast with classical approaches of chemical synthesis.
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Affiliation(s)
- Bertold Rasche
- Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, UK
| | - Minjun Yang
- Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, UK
| | - Lothar Nikonow
- Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, UK
| | - Joshaniel F K Cooper
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0QX, UK
| | | | - Sarah J Day
- Diamond Light Source, Harwell Campus, Didcot, OX11 0QX, UK
| | - Karin Kleiner
- Diamond Light Source, Harwell Campus, Didcot, OX11 0QX, UK
| | - Simon J Clarke
- Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, UK
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20
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Rasche B, Yang M, Nikonow L, Cooper JFK, Murray CA, Day SJ, Kleiner K, Clarke SJ, Compton RG. Elektrochemische In‐situ‐Röntgenbeugung: Eine präzise Methode zur Navigation in Phasendiagrammen enthüllt β‐Fe 1+xSe als Supraleiter für alle x. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201907426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Bertold Rasche
- Department of Chemistry University of Oxford Oxford OX1 3QZ Großbritannien
| | - Minjun Yang
- Department of Chemistry University of Oxford Oxford OX1 3QZ Großbritannien
| | - Lothar Nikonow
- Department of Chemistry University of Oxford Oxford OX1 3QZ Großbritannien
| | - Joshaniel F. K. Cooper
- ISIS Neutron and Muon Source Rutherford Appleton Laboratory Harwell Campus Didcot OX11 0QX Großbritannien
| | - Claire A. Murray
- Diamond Light Source Harwell Campus Didcot OX11 0QX Großbritannien
| | - Sarah J. Day
- Diamond Light Source Harwell Campus Didcot OX11 0QX Großbritannien
| | - Karin Kleiner
- Diamond Light Source Harwell Campus Didcot OX11 0QX Großbritannien
| | - Simon J. Clarke
- Department of Chemistry University of Oxford Oxford OX1 3QZ Großbritannien
| | - Richard G. Compton
- Department of Chemistry University of Oxford Oxford OX1 3QZ Großbritannien
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21
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Le C, Zeng J, Gu Y, Cao GH, Hu J. A possible family of Ni-based high temperature superconductors. Sci Bull (Beijing) 2018; 63:957-963. [PMID: 36658891 DOI: 10.1016/j.scib.2018.06.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 05/11/2018] [Accepted: 05/28/2018] [Indexed: 01/21/2023]
Abstract
We suggest that a family of Ni-based compounds, which contain [Ni2M2O]2- (M = chalcogen) layers with an antiperovskite structure constructed by mixed-anion Ni complexes, NiM4O2, can be potential high temperature superconductors (high-Tc) upon doping or applying pressure. The layer structures have been formed in many other transitional metal compounds such as La2B2Se2O3 (B = Mn, Fe, Co). For the Ni-based compounds, we predict that the parental compounds host collinear antiferromagnetic states similar to those in iron-based high temperature superconductors. The electronic physics near Fermi energy is controlled by two egd-orbitals with completely independent in-plane kinematics. We predict that the superconductivity in this family is characterized by strong competition between extended s-wave and d-wave pairing symmetries.
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Affiliation(s)
- Congcong Le
- Kavli Institute of Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China; Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jinfeng Zeng
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuhao Gu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China; Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Guang-Han Cao
- Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - Jiangping Hu
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Kavli Institute of Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China; Collaborative Innovation Center of Quantum Matter, Beijing 100049, China.
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22
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Yang FB. Hybridization Induced Competitive Scanning Tunneling Interference Process into a Heavy Fermion System. CHINESE PHYSICS LETTERS 2018; 35:077502. [DOI: 10.1088/0256-307x/35/7/077502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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23
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Wang Y, Chen CC, Moritz B, Devereaux TP. Light-Enhanced Spin Fluctuations and d-Wave Superconductivity at a Phase Boundary. PHYSICAL REVIEW LETTERS 2018; 120:246402. [PMID: 29957014 DOI: 10.1103/physrevlett.120.246402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Indexed: 06/08/2023]
Abstract
Time-domain techniques have shown the potential of photomanipulating existing orders and inducing new states of matter in strongly correlated materials. Using time-resolved exact diagonalization, we perform numerical studies of pump dynamics in a Mott-Peierls system with competing charge and spin density waves. A light-enhanced d-wave superconductivity is observed when the system resides near a quantum phase boundary. By examining the evolution of spin, charge, and superconducting susceptibilities, we show that a subdominant state in equilibrium can be stabilized by photomanipulating the charge order to allow superconductivity to appear and dominate. This work provides an interpretation of light-induced superconductivity from the perspective of order competition and offers a promising approach for designing novel emergent states out of equilibrium.
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Affiliation(s)
- Yao Wang
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
- SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Cheng-Chien Chen
- Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - B Moritz
- SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Physics and Astrophysics, University of North Dakota, Grand Forks, North Dakota 58202, USA
| | - T P Devereaux
- SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
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24
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Salazar C, Baumann D, Hänke T, Scheffler M, Kühne T, Kaiser M, Voigtländer R, Lindackers D, Büchner B, Hess C. An ultra-high vacuum scanning tunneling microscope operating at sub-Kelvin temperatures and high magnetic fields for spin-resolved measurements. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:065104. [PMID: 29960518 DOI: 10.1063/1.5027782] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present the construction and performance of an ultra-low-temperature scanning tunneling microscope (STM), working in ultra-high vacuum (UHV) conditions and in high magnetic fields up to 9 T. The cryogenic environment of the STM is generated by a single-shot 3He magnet cryostat in combination with a 4He dewar system. At a base temperature (300 mK), the cryostat has an operation time of approximately 80 h. The special design of the microscope allows the transfer of the STM head from the cryostat to a UHV chamber system, where samples and STM tips can be easily exchanged. The UHV chambers are equipped with specific surface science treatment tools for the functionalization of samples and tips, including high-temperature treatments and thin film deposition. This, in particular, enables spin-resolved tunneling measurements. We present test measurements using well-known samples and tips based on superconductors and metallic materials such as LiFeAs, Nb, Fe, and W. The measurements demonstrate the outstanding performance of the STM with high spatial and energy resolution as well as the spin-resolved capability.
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Affiliation(s)
- C Salazar
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - D Baumann
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - T Hänke
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - M Scheffler
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - T Kühne
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - M Kaiser
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - R Voigtländer
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - D Lindackers
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - B Büchner
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - C Hess
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
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25
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Gu Y, Liu Z, Xie T, Zhang W, Gong D, Hu D, Ma X, Li C, Zhao L, Lin L, Xu Z, Tan G, Chen G, Meng ZY, Yang YF, Luo H, Li S. Unified Phase Diagram for Iron-Based Superconductors. PHYSICAL REVIEW LETTERS 2017; 119:157001. [PMID: 29077435 DOI: 10.1103/physrevlett.119.157001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Indexed: 06/07/2023]
Abstract
High-temperature superconductivity is closely adjacent to a long-range antiferromagnet, which is called a parent compound. In cuprates, all parent compounds are alike and carrier doping leads to superconductivity, so a unified phase diagram can be drawn. However, the properties of parent compounds for iron-based superconductors show significant diversity and both carrier and isovalent dopings can cause superconductivity, which casts doubt on the idea that there exists a unified phase diagram for them. Here we show that the ordered moments in a variety of iron pnictides are inversely proportional to the effective Curie constants of their nematic susceptibility. This unexpected scaling behavior suggests that the magnetic ground states of iron pnictides can be achieved by tuning the strength of nematic fluctuations. Therefore, a unified phase diagram can be established where superconductivity emerges from a hypothetical parent compound with a large ordered moment but weak nematic fluctuations, which suggests that iron-based superconductors are strongly correlated electron systems.
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Affiliation(s)
- Yanhong Gu
- 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
| | - Zhaoyu 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
| | - Tao Xie
- 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
| | - Wenliang Zhang
- 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
| | - Dongliang Gong
- 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
| | - Ding Hu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaoyan Ma
- 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
| | - Chunhong Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Lingxiao Zhao
- 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
| | - Lifang Lin
- Beijing Normal University, Beijing 100875, China
| | - Zhuang Xu
- Beijing Normal University, Beijing 100875, China
| | - Guotai Tan
- Beijing Normal University, Beijing 100875, China
| | - Genfu Chen
- 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
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - Zi Yang Meng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yi-Feng Yang
- 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
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - Huiqian Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Shiliang Li
- 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
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
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26
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Wang Z, Liu C, Liu Y, Wang J. High-temperature superconductivity in one-unit-cell FeSe films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:153001. [PMID: 28176680 DOI: 10.1088/1361-648x/aa5f26] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Since the dramatic enhancement of the superconducting transition temperature (T c) was reported in a one-unit-cell FeSe film grown on a SrTiO3 substrate (1-UC FeSe/STO) by molecular beam epitaxy (MBE), related research on this system has become a new frontier in condensed matter physics. In this paper, we present a brief review on this rapidly developing field, mainly focusing on the superconducting properties of 1-UC FeSe/STO. Experimental evidence for high-temperature superconductivity in 1-UC FeSe/STO, including direct evidence revealed by transport and diamagnetic measurements, as well as other evidence from scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES), are overviewed. The potential mechanisms of the enhanced superconductivity are also discussed. There are accumulating arguments to suggest that the strengthened Cooper pairing in 1-UC FeSe/STO originates from the interface effects, specifically the charge transfer and coupling to phonon modes in the TiO2 plane. The study of superconductivity in 1-UC FeSe/STO not only sheds new light on the mechanism of high-temperature superconductors with layered structures, but also provides an insight into the exploration of new superconductors by interface engineering.
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Affiliation(s)
- Ziqiao Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
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27
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Xu Y, Liu S, Qu N, Cui Y, Gao Q, Chen R, Wang J, Gao F, Hao X. Comparative description of magnetic interactions in Sr 2CuTeO 6 and Sr 2CuWO 6. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:105801. [PMID: 28145278 DOI: 10.1088/1361-648x/aa58cb] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this work, we comparatively explored the electronic structure and the low-dimensional magnetic interactions of double-perovskite compounds Sr2CuTeO6 and Sr2CuWO6 through first-principles calculations. The electronic structure calculations indicate that the Cu2+ (3d 9) site is the only magnetic active one, whereas Te6+ and W6+ remain in nonmagnetic states with d 10 and d 0 electronic configurations, respectively. The magnetic exchange interactions have been evaluated on the basis of the classical Heisenberg model. Both Sr2CuTeO6 and Sr2CuWO6 should be strong frustrated 2D magnetism, in excellent agreement with the experimental observations. Nevertheless, the nearest-neighbor antiferromagnetic interaction J 1 plays a determined role in constructing the Néel antiferromagnetic ordering within the square Cu2+ framework of Sr2CuTeO6. While, the next-nearest-neighbor antiferromagnetic interaction J 2 transcends the nearest-neighbor interaction J 1, establishes the collinear antiferromagnetic ordering in Sr2CuWO6. The discrimination has been explored and analyzed in detail using density of states, charge density as well as spin density analysis.
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Affiliation(s)
- Yuanhui Xu
- Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao 066004, People's Republic of China
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28
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Hu J, Le C. A possible new family of unconventional high temperature superconductors. Sci Bull (Beijing) 2017; 62:212-217. [PMID: 36659408 DOI: 10.1016/j.scib.2016.12.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 12/26/2016] [Accepted: 12/26/2016] [Indexed: 01/21/2023]
Abstract
We suggest a new family of Co/Ni-based materials that may host unconventional high temperature superconductivity (high-Tc). These materials carry layered square lattices with each layer being formed by vertex-shared transition metal tetrahedra cation-anion complexes. The electronic physics in these materials is determined by the two dimensional layer and is fully attributed to the three near degenerated t2gd-orbitals close to a d7 filling configuration in the d-shell of Co/Ni atoms. The electronic structure meets the necessary criteria for unconventional high Tc materials proposed recently by us to unify the two known high-Tc families, cuprates and iron-based superconductors. We predict that they host superconducting states with a d-wave pairing symmetry with Tc potentially higher than those of iron-based superconductors. These materials, if realized, can be a fertile new ground to study strongly correlated electronic physics and provide decisive evidence for superconducting pairing mechanism.
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Affiliation(s)
- Jiangping Hu
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Collaborative Innovation Center of Quantum Matter, Beijing 100871, China; School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Congcong Le
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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29
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Guterding D, Jeschke HO, Mazin II, Glasbrenner JK, Bascones E, Valentí R. Nontrivial Role of Interlayer Cation States in Iron-Based Superconductors. PHYSICAL REVIEW LETTERS 2017; 118:017204. [PMID: 28106450 DOI: 10.1103/physrevlett.118.017204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Indexed: 06/06/2023]
Abstract
Unconventional superconductivity in iron pnictides and chalcogenides has been suggested to be controlled by the interplay of low-energy antiferromagnetic spin fluctuations and the particular topology of the Fermi surface in these materials. Based on this premise, one would also expect the large class of isostructural and isoelectronic iron germanide compounds to be good superconductors. As a matter of fact, they, however, superconduct at very low temperatures or not at all. In this work we establish that superconductivity in iron germanides is suppressed by strong ferromagnetic tendencies, which surprisingly do not originate from changes in bond angles or bond distances with respect to iron pnictides and chalcogenides, but are due to changes in the electronic structure in a wide range of energies happening upon substitution of atom species (As by Ge and the corresponding spacer cations). Our results indicate that superconductivity in iron-based materials may not always be fully understood based on d or d-p model Hamiltonians only.
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Affiliation(s)
- Daniel Guterding
- Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - Harald O Jeschke
- Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - I I Mazin
- Code 6393, Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - J K Glasbrenner
- National Research Council/Code 6393, Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - E Bascones
- Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, Cantoblanco, 28049 Madrid, Spain
| | - Roser Valentí
- Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
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30
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Fernandes RM, Chubukov AV. Low-energy microscopic models for iron-based superconductors: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:014503. [PMID: 27876709 DOI: 10.1088/1361-6633/80/1/014503] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The development of sensible microscopic models is essential to elucidate the normal-state and superconducting properties of the iron-based superconductors. Because these materials are mostly metallic, a good starting point is an effective low-energy model that captures the electronic states near the Fermi level and their interactions. However, in contrast to cuprates, iron-based high-T c compounds are multi-orbital systems with Hubbard and Hund interactions, resulting in a rather involved 10-orbital lattice model. Here we review different minimal models that have been proposed to unveil the universal features of these systems. We first review minimal models defined solely in the orbital basis, which focus on a particular subspace of orbitals, or solely in the band basis, which rely only on the geometry of the Fermi surface. The former, while providing important qualitative insight into the role of the orbital degrees of freedom, do not distinguish between high-energy and low-energy sectors and, for this reason, generally do not go beyond mean-field. The latter allow one to go beyond mean-field and investigate the interplay between superconducting and magnetic orders as well as Ising-nematic order. However, they cannot capture orbital-dependent features like spontaneous orbital order. We then review recent proposals for a minimal model that operates in the band basis but fully incorporates the orbital composition and symmetries of the low-energy excitations. We discuss the results of the renormalization group study of such a model, particularly of the interplay between superconductivity, magnetism, and spontaneous orbital order, and compare theoretical predictions with experiments on iron pnictides and chalcogenides. We also discuss the impact of the glide-plane symmetry on the low-energy models, highlighting the key role played by the spin-orbit coupling.
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31
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Morr DK. Theory of scanning tunneling spectroscopy: from Kondo impurities to heavy fermion materials. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:014502. [PMID: 27823990 DOI: 10.1088/0034-4885/80/1/014502] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Kondo systems ranging from the single Kondo impurity to heavy fermion materials present us with a plethora of unconventional properties whose theoretical understanding is still one of the major open problems in condensed matter physics. Over the last few years, groundbreaking scanning tunneling spectroscopy (STS) experiments have provided unprecedented new insight into the electronic structure of Kondo systems. Interpreting the results of these experiments-the differential conductance and the quasi-particle interference spectrum-however, has been complicated by the fact that electrons tunneling from the STS tip into the system can tunnel either into the heavy magnetic moment or the light conduction band states. In this article, we briefly review the theoretical progress made in understanding how quantum interference between these two tunneling paths affects the experimental STS results. We show how this theoretical insight has allowed us to interpret the results of STS experiments on a series of heavy fermion materials providing detailed knowledge of their complex electronic structure. It is this knowledge that is a conditio sine qua non for developing a deeper understanding of the fascinating properties exhibited by heavy fermion materials, ranging from unconventional superconductivity to non-Fermi-liquid behavior in the vicinity of quantum critical points.
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Affiliation(s)
- Dirk K Morr
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
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32
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Ekino T, Gabovich AM, Suan Li M, Szymczak H, Voitenko AI. Influence of the spatially inhomogeneous gap distribution on the quasiparticle current in c-axis junctions involving d-wave superconductors with charge density waves. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:445701. [PMID: 27604150 DOI: 10.1088/0953-8984/28/44/445701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The quasiparticle tunnel current J(V) between the superconducting ab-planes along the c-axis and the corresponding conductance [Formula: see text] were calculated for symmetric junctions composed of disordered d-wave layered superconductors partially gapped by charge density waves (CDWs). Here, V is the voltage. Both the checkerboard and unidirectional CDWs were considered. It was shown that the spatial spread of the CDW-pairing strength substantially smears the peculiarities of G(V) appropriate to uniform superconductors. The resulting curves G(V) become very similar to those observed for a number of cuprates in intrinsic junctions, e.g. mesas. In particular, the influence of CDWs may explain the peak-dip-hump structures frequently found for high-T c oxides.
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Affiliation(s)
- T Ekino
- Hiroshima University, Graduate School of Integrated Arts and Sciences, Higashi-Hiroshima, 739-8521, Japan
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33
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Commensurate 4 a0-period charge density modulations throughout the Bi 2Sr 2CaCu 2O 8+x pseudogap regime. Proc Natl Acad Sci U S A 2016; 113:12661-12666. [PMID: 27791157 DOI: 10.1073/pnas.1614247113] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Theories based upon strong real space (r-space) electron-electron interactions have long predicted that unidirectional charge density modulations (CDMs) with four-unit-cell (4a0) periodicity should occur in the hole-doped cuprate Mott insulator (MI). Experimentally, however, increasing the hole density p is reported to cause the conventionally defined wavevector QA of the CDM to evolve continuously as if driven primarily by momentum-space (k-space) effects. Here we introduce phase-resolved electronic structure visualization for determination of the cuprate CDM wavevector. Remarkably, this technique reveals a virtually doping-independent locking of the local CDM wavevector at [Formula: see text] throughout the underdoped phase diagram of the canonical cuprate Bi2Sr2CaCu2O8 These observations have significant fundamental consequences because they are orthogonal to a k-space (Fermi-surface)-based picture of the cuprate CDMs but are consistent with strong-coupling r-space-based theories. Our findings imply that it is the latter that provides the intrinsic organizational principle for the cuprate CDM state.
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Gyenis A, da Silva Neto EH, Sutarto R, Schierle E, He F, Weschke E, Kavai M, Baumbach RE, Thompson JD, Bauer ED, Fisk Z, Damascelli A, Yazdani A, Aynajian P. Quasi-particle interference of heavy fermions in resonant x-ray scattering. SCIENCE ADVANCES 2016; 2:e1601086. [PMID: 27757422 PMCID: PMC5065254 DOI: 10.1126/sciadv.1601086] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 09/16/2016] [Indexed: 06/06/2023]
Abstract
Resonant x-ray scattering (RXS) has recently become an increasingly important tool for the study of ordering phenomena in correlated electron systems. Yet, the interpretation of RXS experiments remains theoretically challenging because of the complexity of the RXS cross section. Central to this debate is the recent proposal that impurity-induced Friedel oscillations, akin to quasi-particle interference signals observed with a scanning tunneling microscope (STM), can lead to scattering peaks in RXS experiments. The possibility that quasi-particle properties can be probed in RXS measurements opens up a new avenue to study the bulk band structure of materials with the orbital and element selectivity provided by RXS. We test these ideas by combining RXS and STM measurements of the heavy fermion compound CeMIn5 (M = Co, Rh). Temperature- and doping-dependent RXS measurements at the Ce-M4 edge show a broad scattering enhancement that correlates with the appearance of heavy f-electron bands in these compounds. The scattering enhancement is consistent with the measured quasi-particle interference signal in the STM measurements, indicating that the quasi-particle interference can be probed through the momentum distribution of RXS signals. Overall, our experiments demonstrate new opportunities for studies of correlated electronic systems using the RXS technique.
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Affiliation(s)
- András Gyenis
- Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Eduardo H. da Silva Neto
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
- Quantum Materials Program, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
| | - Ronny Sutarto
- Canadian Light Source, Saskatoon, Saskatchewan S7N 2V3, Canada
| | - Enrico Schierle
- Helmholtz-Zentrum Berlin fürMaterialien und Energie, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - Feizhou He
- Helmholtz-Zentrum Berlin fürMaterialien und Energie, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - Eugen Weschke
- Helmholtz-Zentrum Berlin fürMaterialien und Energie, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - Mariam Kavai
- Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, NY 13902, USA
| | | | | | - Eric D. Bauer
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Zachary Fisk
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697, USA
| | - Andrea Damascelli
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Ali Yazdani
- Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Pegor Aynajian
- Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, NY 13902, USA
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35
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Antipov AE, Javanmard Y, Ribeiro P, Kirchner S. Interaction-Tuned Anderson versus Mott Localization. PHYSICAL REVIEW LETTERS 2016; 117:146601. [PMID: 27740798 DOI: 10.1103/physrevlett.117.146601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Indexed: 06/06/2023]
Abstract
Disorder or sufficiently strong interactions can render a metallic state unstable, causing it to turn into an insulating one. Despite the fact that the interplay of these two routes to a vanishing conductivity has been a central research topic, a unifying picture has not emerged so far. Here, we establish that the two-dimensional Falicov-Kimball model, one of the simplest lattice models of strong electron correlation, does allow for the study of this interplay. In particular, we show that this model at particle-hole symmetry possesses three distinct thermodynamic insulating phases and exhibits Anderson localization. The previously reported metallic phase is identified as a finite-size feature due to the presence of weak localization. We characterize these phases by their electronic density of states, staggered occupation, conductivity, and the generalized inverse participation ratio. The implications of our findings for other strongly correlated systems are discussed.
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Affiliation(s)
- Andrey E Antipov
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Younes Javanmard
- Max-Planck-Institut für Physik komplexer Systeme, 01187 Dresden, Germany
| | - Pedro Ribeiro
- CeFEMA, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisboa, Portugal
- Russian Quantum Center, 143025 Skolkovo, Moscow region, Russia
| | - Stefan Kirchner
- Center for Correlated Matter, Zhejiang University, Hangzhou, Zhejiang 310058, China
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da Silva Neto EH, Yu B, Minola M, Sutarto R, Schierle E, Boschini F, Zonno M, Bluschke M, Higgins J, Li Y, Yu G, Weschke E, He F, Le Tacon M, Greene RL, Greven M, Sawatzky GA, Keimer B, Damascelli A. Doping-dependent charge order correlations in electron-doped cuprates. SCIENCE ADVANCES 2016; 2:e1600782. [PMID: 27536726 PMCID: PMC4982707 DOI: 10.1126/sciadv.1600782] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 07/14/2016] [Indexed: 05/25/2023]
Abstract
Understanding the interplay between charge order (CO) and other phenomena (for example, pseudogap, antiferromagnetism, and superconductivity) is one of the central questions in the cuprate high-temperature superconductors. The discovery that similar forms of CO exist in both hole- and electron-doped cuprates opened a path to determine what subset of the CO phenomenology is universal to all the cuprates. We use resonant x-ray scattering to measure the CO correlations in electron-doped cuprates (La2-x Ce x CuO4 and Nd2-x Ce x CuO4) and their relationship to antiferromagnetism, pseudogap, and superconductivity. Detailed measurements of Nd2-x Ce x CuO4 show that CO is present in the x = 0.059 to 0.166 range and that its doping-dependent wave vector is consistent with the separation between straight segments of the Fermi surface. The CO onset temperature is highest between x = 0.106 and 0.166 but decreases at lower doping levels, indicating that it is not tied to the appearance of antiferromagnetic correlations or the pseudogap. Near optimal doping, where the CO wave vector is also consistent with a previously observed phonon anomaly, measurements of the CO below and above the superconducting transition temperature, or in a magnetic field, show that the CO is insensitive to superconductivity. Overall, these findings indicate that, although verified in the electron-doped cuprates, material-dependent details determine whether the CO correlations acquire sufficient strength to compete for the ground state of the cuprates.
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Affiliation(s)
- Eduardo H. da Silva Neto
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
- Quantum Materials Program, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
| | - Biqiong Yu
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - Matteo Minola
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Ronny Sutarto
- Canadian Light Source, Saskatoon, Saskatchewan S7N 2V3, Canada
| | - Enrico Schierle
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - Fabio Boschini
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Marta Zonno
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Martin Bluschke
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - Joshua Higgins
- Center for Nanophysics and Advanced Materials, University of Maryland, College Park, MD 20742, USA
| | - Yangmu Li
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - Guichuan Yu
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - Eugen Weschke
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - Feizhou He
- Canadian Light Source, Saskatoon, Saskatchewan S7N 2V3, Canada
| | - Mathieu Le Tacon
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
- Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76201 Karlsruhe, Germany
| | - Richard L. Greene
- Center for Nanophysics and Advanced Materials, University of Maryland, College Park, MD 20742, USA
| | - Martin Greven
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - George A. Sawatzky
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Bernhard Keimer
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Andrea Damascelli
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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Sun JP, Matsuura K, Ye GZ, Mizukami Y, Shimozawa M, Matsubayashi K, Yamashita M, Watashige T, Kasahara S, Matsuda Y, Yan JQ, Sales BC, Uwatoko Y, Cheng JG, Shibauchi T. Dome-shaped magnetic order competing with high-temperature superconductivity at high pressures in FeSe. Nat Commun 2016; 7:12146. [PMID: 27431724 PMCID: PMC4960320 DOI: 10.1038/ncomms12146] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 06/05/2016] [Indexed: 11/24/2022] Open
Abstract
The coexistence and competition between superconductivity and electronic orders, such as spin or charge density waves, have been a central issue in high transition-temperature (Tc) superconductors. Unlike other iron-based superconductors, FeSe exhibits nematic ordering without magnetism whose relationship with its superconductivity remains unclear. Moreover, a pressure-induced fourfold increase of Tc has been reported, which poses a profound mystery. Here we report high-pressure magnetotransport measurements in FeSe up to ∼15 GPa, which uncover the dome shape of magnetic phase superseding the nematic order. Above ∼6 GPa the sudden enhancement of superconductivity (Tc≤38.3 K) accompanies a suppression of magnetic order, demonstrating their competing nature with very similar energy scales. Above the magnetic dome, we find anomalous transport properties suggesting a possible pseudogap formation, whereas linear-in-temperature resistivity is observed in the normal states of the high-Tc phase above 6 GPa. The obtained phase diagram highlights unique features of FeSe among iron-based superconductors, but bears some resemblance to that of high-Tc cuprates.
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Affiliation(s)
- J. P. Sun
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - K. Matsuura
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - G. Z. Ye
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Science and Technology, Yunnan University, Kunming 650091, China
| | - Y. Mizukami
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - M. Shimozawa
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - K. Matsubayashi
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
| | - M. Yamashita
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - T. Watashige
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - S. Kasahara
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Y. Matsuda
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - J. -Q. Yan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - B. C. Sales
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Y. Uwatoko
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - J. -G. Cheng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - T. Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
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Paglione J, Tanatar MA, Reid JP, Shakeripour H, Petrovic C, Taillefer L. Quantum Critical Quasiparticle Scattering within the Superconducting State of CeCoIn_{5}. PHYSICAL REVIEW LETTERS 2016; 117:016601. [PMID: 27419578 DOI: 10.1103/physrevlett.117.016601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Indexed: 06/06/2023]
Abstract
The thermal conductivity κ of the heavy-fermion metal CeCoIn_{5} was measured in the normal and superconducting states as a function of temperature T and magnetic field H, for a current and field parallel to the [100] direction. Inside the superconducting state, when the field is lower than the upper critical field H_{c2}, κ/T is found to increase as T→0, just as in a metal and in contrast to the behavior of all known superconductors. This is due to unpaired electrons on part of the Fermi surface, which dominate the transport above a certain field. The evolution of κ/T with field reveals that the electron-electron scattering (or transport mass m^{⋆}) of those unpaired electrons diverges as H→H_{c2} from below, in the same way that it does in the normal state as H→H_{c2} from above. This shows that the unpaired electrons sense the proximity of the field-tuned quantum critical point of CeCoIn_{5} at H^{⋆}=H_{c2} even from inside the superconducting state. The fact that the quantum critical scattering of the unpaired electrons is much weaker than the average scattering of all electrons in the normal state reveals a k-space correlation between the strength of pairing and the strength of scattering, pointing to a common mechanism, presumably antiferromagnetic fluctuations.
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Affiliation(s)
- Johnpierre Paglione
- Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
- Canadian Institute for Advanced Research, Toronto, Canada M5G 1Z8
| | - M A Tanatar
- Département de physique & RQMP, Université de Sherbrooke, Sherbrooke, Canada J1K 2R1
- Ames Laboratory USDOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - J-Ph Reid
- Département de physique & RQMP, Université de Sherbrooke, Sherbrooke, Canada J1K 2R1
| | - H Shakeripour
- Department of Physics, Isfahan University of Technology, Isfahan 84156-83111, Iran
| | - C Petrovic
- Canadian Institute for Advanced Research, Toronto, Canada M5G 1Z8
- Department of Physics, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Louis Taillefer
- Canadian Institute for Advanced Research, Toronto, Canada M5G 1Z8
- Département de physique & RQMP, Université de Sherbrooke, Sherbrooke, Canada J1K 2R1
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Li ZX, Wang F, Yao H, Lee DH. What makes the Tc of monolayer FeSe on SrTiO 3 so high: a sign-problem-free quantum Monte Carlo study. Sci Bull (Beijing) 2016; 61:925-930. [PMID: 27398243 PMCID: PMC4914519 DOI: 10.1007/s11434-016-1087-x] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 04/18/2016] [Accepted: 04/18/2016] [Indexed: 11/29/2022]
Abstract
Monolayer FeSe films grown on SrTiO3 (STO) substrate show superconducting gap-opening temperatures (\documentclass[12pt]{minimal}
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\begin{document}$$T_{\mathrm{c}}$$\end{document}Tc) which are almost an order of magnitude higher than those of the bulk FeSe and are highest among all known Fe-based superconductors. Angle-resolved photoemission spectroscopy observed “replica bands” suggesting the importance of the interaction between FeSe electrons and STO phonons. These facts rejuvenated the quest for \documentclass[12pt]{minimal}
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\begin{document}$$T_{{\mathrm{c}}}$$\end{document}Tc enhancement mechanisms in iron-based, especially iron-chalcogenide, superconductors. Here, we perform the first numerically-exact sign-problem-free quantum Monte Carlo simulations to iron-based superconductors. We (1) study the electronic pairing mechanism intrinsic to heavily electron doped FeSe films, and (2) examine the effects of electron–phonon interaction between FeSe and STO as well as nematic fluctuations on \documentclass[12pt]{minimal}
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\begin{document}$$T_{{\mathrm{c}}}$$\end{document}Tc. Armed with these results, we return to the question “what makes the \documentclass[12pt]{minimal}
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\begin{document}$$T_{{\mathrm{c}}}$$\end{document}Tc of monolayer FeSe on SrTiO3 so high?” in the conclusion and discussions.
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Affiliation(s)
- Zi-Xiang Li
- />Institute for Advanced Study, Tsinghua University, Beijing, 100084 China
| | - Fa Wang
- />International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871 China
- />Collaborative Innovation Center of Quantum Matter, Beijing, 100871 China
| | - Hong Yao
- />Institute for Advanced Study, Tsinghua University, Beijing, 100084 China
- />Collaborative Innovation Center of Quantum Matter, Beijing, 100871 China
| | - Dung-Hai Lee
- />Department of Physics, University of California, Berkeley, CA 94720 USA
- />Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
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41
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The rate of quasiparticle recombination probes the onset of coherence in cuprate superconductors. Sci Rep 2016; 6:23610. [PMID: 27071712 PMCID: PMC4829850 DOI: 10.1038/srep23610] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 03/03/2016] [Indexed: 11/08/2022] Open
Abstract
In the underdoped copper-oxides, high-temperature superconductivity condenses from a nonconventional metallic ”pseudogap” phase that exhibits a variety of non-Fermi liquid properties. Recently, it has become clear that a charge density wave (CDW) phase exists within the pseudogap regime. This CDW coexists and competes with superconductivity (SC) below the transition temperature Tc, suggesting that these two orders are intimately related. Here we show that the condensation of the superfluid from this unconventional precursor is reflected in deviations from the predictions of BSC theory regarding the recombination rate of quasiparticles. We report a detailed investigation of the quasiparticle (QP) recombination lifetime, τqp, as a function of temperature and magnetic field in underdoped HgBa2CuO4+δ (Hg-1201) and YBa2Cu3O6+x (YBCO) single crystals by ultrafast time-resolved reflectivity. We find that τqp(T ) exhibits a local maximum in a small temperature window near Tc that is prominent in underdoped samples with coexisting charge order and vanishes with application of a small magnetic field. We explain this unusual, non-BCS behavior by positing that Tc marks a transition from phase-fluctuating SC/CDW composite order above to a SC/CDW condensate below. Our results suggest that the superfluid in underdoped cuprates is a condensate of coherently-mixed particle-particle and particle-hole pairs.
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42
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Coexistence of charge and ferromagnetic order in fcc Fe. Nat Commun 2016; 7:10949. [PMID: 26971713 PMCID: PMC4793077 DOI: 10.1038/ncomms10949] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 02/04/2016] [Indexed: 11/09/2022] Open
Abstract
Phase coexistence phenomena have been intensively studied in strongly correlated materials where several ordered states simultaneously occur or compete. Material properties critically depend on external parameters and boundary conditions, where tiny changes result in qualitatively different ground states. However, up to date, phase coexistence phenomena have exclusively been reported for complex compounds composed of multiple elements. Here we show that charge- and magnetically ordered states coexist in double-layer Fe/Rh(001). Scanning tunnelling microscopy and spectroscopy measurements reveal periodic charge-order stripes below a temperature of 130 K. Close to liquid helium temperature, they are superimposed by ferromagnetic domains as observed by spin-polarized scanning tunnelling microscopy. Temperature-dependent measurements reveal a pronounced cross-talk between charge and spin order at the ferromagnetic ordering temperature about 70 K, which is successfully modelled within an effective Ginzburg-Landau ansatz including sixth-order terms. Our results show that subtle balance between structural modifications can lead to competing ordering phenomena.
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43
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Wang Y, Moritz B, Chen CC, Jia CJ, van Veenendaal M, Devereaux TP. Using Nonequilibrium Dynamics to Probe Competing Orders in a Mott-Peierls System. PHYSICAL REVIEW LETTERS 2016; 116:086401. [PMID: 26967429 DOI: 10.1103/physrevlett.116.086401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Indexed: 06/05/2023]
Abstract
Competition between ordered phases, and their associated phase transitions, are significant in the study of strongly correlated systems. Here, we examine one aspect, the nonequilibrium dynamics of a photoexcited Mott-Peierls system, using an effective Peierls-Hubbard model and exact diagonalization. Near a transition where spin and charge become strongly intertwined, we observe antiphase dynamics and a coupling-strength-dependent suppression or enhancement in the static structure factors. The renormalized bosonic excitations coupled to a particular photoexcited electron can be extracted, which provides an approach for characterizing the underlying bosonic modes. The results from this analysis for different electronic momenta show an uneven softening due to a stronger coupling near k_{F}. This behavior reflects the strong link between the fermionic momenta, the coupling vertices, and ultimately, the bosonic susceptibilities when multiple phases compete for the ground state of the system.
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Affiliation(s)
- Y Wang
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
- SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - B Moritz
- SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Physics and Astrophysics, University of North Dakota, Grand Forks, North Dakota 58202, USA
| | - C-C Chen
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - C J Jia
- SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - M van Veenendaal
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
- Department of Physics, Northern Illinois University, De Kalb, Illinois 60115, USA
| | - T P Devereaux
- SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
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44
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Tu WL, Lee TK. Genesis of charge orders in high temperature superconductors. Sci Rep 2016; 6:18675. [PMID: 26732076 PMCID: PMC4702086 DOI: 10.1038/srep18675] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 11/23/2015] [Indexed: 11/10/2022] Open
Abstract
One of the most puzzling facts about cuprate high-temperature superconductors in the lightly doped regime is the coexistence of uniform superconductivity and/or antiferromagnetism with many low-energy charge-ordered states in a unidirectional charge density wave or a bidirectional checkerboard structure. Recent experiments have discovered that these charge density waves exhibit different symmetries in their intra-unit-cell form factors for different cuprate families. Using a renormalized mean-field theory for a well-known, strongly correlated model of cuprates, we obtain a number of charge-ordered states with nearly degenerate energies without invoking special features of the Fermi surface. All of these self-consistent solutions have a pair density wave intertwined with a charge density wave and sometimes a spin density wave. Most of these states vanish in the underdoped regime, except for one with a large d-form factor that vanishes at approximately 19% doping of the holes, as reported by experiments. Furthermore, these states could be modified to have a global superconducting order, with a nodal-like density of states at low energy.
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Affiliation(s)
- Wei-Lin Tu
- Department of Physics, National Taiwan University, Daan Taipei 10617, Taiwan
- Institute of Physics, Academia Sinica, Nankang Taipei 11529, Taiwan
| | - Ting-Kuo Lee
- Institute of Physics, Academia Sinica, Nankang Taipei 11529, Taiwan
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45
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Comin R, Sutarto R, He F, da Silva Neto EH, Chauviere L, Fraño A, Liang R, Hardy WN, Bonn DA, Yoshida Y, Eisaki H, Achkar AJ, Hawthorn DG, Keimer B, Sawatzky GA, Damascelli A. Symmetry of charge order in cuprates. NATURE MATERIALS 2015; 14:796-800. [PMID: 26006005 DOI: 10.1038/nmat4295] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 04/16/2015] [Indexed: 05/23/2023]
Abstract
Charge-ordered ground states permeate the phenomenology of 3d-based transition metal oxides, and more generally represent a distinctive hallmark of strongly correlated states of matter. The recent discovery of charge order in various cuprate families has fuelled new interest into the role played by this incipient broken symmetry within the complex phase diagram of high-T(c) superconductors. Here, we use resonant X-ray scattering to resolve the main characteristics of the charge-modulated state in two cuprate families: Bi2Sr(2-x)La(x)CuO(6+δ) (Bi2201) and YBa2Cu3O(6+y) (YBCO). We detect no signatures of spatial modulations along the nodal direction in Bi2201, thus clarifying the inter-unit-cell momentum structure of charge order. We also resolve the intra-unit-cell symmetry of the charge-ordered state, which is revealed to be best represented by a bond order with modulated charges on the O-2p orbitals and a prominent d-wave character. These results provide insights into the origin and microscopic description of charge order in cuprates, and its interplay with superconductivity.
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Affiliation(s)
- R Comin
- 1] Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada [2] Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - R Sutarto
- Canadian Light Source, Saskatoon, Saskatchewan S7N 2V3, Canada
| | - F He
- Canadian Light Source, Saskatoon, Saskatchewan S7N 2V3, Canada
| | - E H da Silva Neto
- 1] Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada [2] Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada [3] Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany [4] Quantum Materials Program, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
| | - L Chauviere
- 1] Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada [2] Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada [3] Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - A Fraño
- 1] Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany [2] Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein Straße 15, 12489 Berlin, Germany
| | - R Liang
- 1] Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada [2] Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - W N Hardy
- 1] Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada [2] Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - D A Bonn
- 1] Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada [2] Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Y Yoshida
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568, Japan
| | - H Eisaki
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568, Japan
| | - A J Achkar
- Department of Physics and Astronomy, University of Waterloo, Waterloo N2L 3G1, Canada
| | - D G Hawthorn
- Department of Physics and Astronomy, University of Waterloo, Waterloo N2L 3G1, Canada
| | - B Keimer
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - G A Sawatzky
- 1] Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada [2] Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - A Damascelli
- 1] Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada [2] Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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Mangin-Thro L, Sidis Y, Wildes A, Bourges P. Intra-unit-cell magnetic correlations near optimal doping in YBa2Cu3O6.85. Nat Commun 2015; 6:7705. [PMID: 26138869 PMCID: PMC4506545 DOI: 10.1038/ncomms8705] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 06/01/2015] [Indexed: 11/09/2022] Open
Abstract
The pseudo-gap phenomenon in copper oxide superconductors is central to any description of these materials as it prefigures the superconducting state itself. A magnetic intra-unit-cell order was found to occur just at the pseudo-gap temperature in four cuprate high-Tc superconducting families. Here we present polarized neutron-scattering measurements of nearly optimally doped YBa2Cu3O6.85, carried out on two different spectrometers, that reveal several features. The intra-unit-cell order consists of finite-sized planar domains that are very weakly correlated along the c axis. At high temperature, only the out-of-plane magnetic components correlate, indicating a strong Ising anisotropy. An aditional in-plane response develops at low temperature, giving rise to an apparent tilt of the magnetic moment. The discovery of these two regimes puts stringent constraints, which are tightly bound to the pseudo-gap physics, on the intrinsic nature of intra-unit-cell order. The pseudo-gap phenomenon is central to the description of high-Tc superconductivity in copper oxides. Here, the authors investigate nearly optimally doped YBCO using polarized neutron scattering to characterize intra-unit-cell magnetic correlations in relation with the pseudo-gap temperature.
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Affiliation(s)
- L Mangin-Thro
- Laboratoire Léon Brillouin, IRAMIS/LLB, UMR12, CEA-CNRS, CEA-Saclay, Gif sur Yvette 91191, France
| | - Y Sidis
- Laboratoire Léon Brillouin, IRAMIS/LLB, UMR12, CEA-CNRS, CEA-Saclay, Gif sur Yvette 91191, France
| | - A Wildes
- Institut Laue-Langevin, 71 avenue des martyrs, Grenoble 38000, France
| | - P Bourges
- Laboratoire Léon Brillouin, IRAMIS/LLB, UMR12, CEA-CNRS, CEA-Saclay, Gif sur Yvette 91191, France
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Das T, Zhu JX, Graf MJ. Theory of nodal s ± -wave pairing symmetry in the Pu-based 115 superconductor family. Sci Rep 2015; 5:8632. [PMID: 25721375 PMCID: PMC4342998 DOI: 10.1038/srep08632] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 01/07/2015] [Indexed: 11/13/2022] Open
Abstract
The spin-fluctuation mechanism of superconductivity usually results in the presence of gapless or nodal quasiparticle states in the excitation spectrum. Nodal quasiparticle states are well established in copper-oxide, and heavy-fermion superconductors, but not in iron-based superconductors. Here, we study the pairing symmetry and mechanism of a new class of plutonium-based high-Tc superconductors and predict the presence of a nodal s+− wave pairing symmetry in this family. Starting from a density-functional theory (DFT) based electronic structure calculation we predict several three-dimensional (3D) Fermi surfaces in this 115 superconductor family. We identify the dominant Fermi surface “hot-spots” in the inter-band scattering channel, which are aligned along the wavevector Q = (π, π, π), where degeneracy could induce sign-reversal of the pairing symmetry. Our calculation demonstrates that the s+− wave pairing strength is stronger than the previously thought d-wave pairing; and more importantly, this pairing state allows for the existence of nodal quasiparticles. Finally, we predict the shape of the momentum- and energy-dependent magnetic resonance spectrum for the identification of this pairing symmetry.
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Affiliation(s)
- Tanmoy Das
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Jian-Xin Zhu
- 1] Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA [2] Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Matthias J Graf
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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da Silva Neto EH, Comin R, He F, Sutarto R, Jiang Y, Greene RL, Sawatzky GA, Damascelli A. Charge ordering in the electron-doped superconductor Nd
2–
x
Ce
x
CuO
4. Science 2015; 347:282-5. [DOI: 10.1126/science.1256441] [Citation(s) in RCA: 162] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Eduardo H. da Silva Neto
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany
- Quantum Materials Program, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
| | - Riccardo Comin
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Feizhou He
- Canadian Light Source, Saskatoon, Saskatchewan S7N 2V3, Canada
| | - Ronny Sutarto
- Canadian Light Source, Saskatoon, Saskatchewan S7N 2V3, Canada
| | - Yeping Jiang
- Center for Nanophysics and Advanced Materials and Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - Richard L. Greene
- Center for Nanophysics and Advanced Materials and Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - George A. Sawatzky
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Andrea Damascelli
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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Miao H, Qian T, Shi X, Richard P, Kim TK, Hoesch M, Xing LY, Wang XC, Jin CQ, Hu JP, Ding H. Observation of strong electron pairing on bands without Fermi surfaces in LiFe1−xCoxAs. Nat Commun 2015; 6:6056. [PMID: 25583450 DOI: 10.1038/ncomms7056] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Accepted: 12/09/2014] [Indexed: 11/10/2022] Open
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50
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Interfacial mode coupling as the origin of the enhancement of T(c) in FeSe films on SrTiO3. Nature 2014; 515:245-8. [PMID: 25391962 DOI: 10.1038/nature13894] [Citation(s) in RCA: 204] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 09/25/2014] [Indexed: 11/08/2022]
Abstract
Films of iron selenide (FeSe) one unit cell thick grown on strontium titanate (SrTiO3 or STO) substrates have recently shown superconducting energy gaps opening at temperatures close to the boiling point of liquid nitrogen (77 kelvin), which is a record for the iron-based superconductors. The gap opening temperature usually sets the superconducting transition temperature Tc, as the gap signals the formation of Cooper pairs, the bound electron states responsible for superconductivity. To understand why Cooper pairs form at such high temperatures, we examine the role of the SrTiO3 substrate. Here we report high-resolution angle-resolved photoemission spectroscopy results that reveal an unexpected characteristic of the single-unit-cell FeSe/SrTiO3 system: shake-off bands suggesting the presence of bosonic modes, most probably oxygen optical phonons in SrTiO3 (refs 5, 6, 7), which couple to the FeSe electrons with only a small momentum transfer. Such interfacial coupling assists superconductivity in most channels, including those mediated by spin fluctuations. Our calculations suggest that this coupling is responsible for raising the superconducting gap opening temperature in single-unit-cell FeSe/SrTiO3.
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