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Pasquale G, Sun Z, Migliato Marega G, Watanabe K, Taniguchi T, Kis A. Electrically tunable giant Nernst effect in two-dimensional van der Waals heterostructures. NATURE NANOTECHNOLOGY 2024; 19:941-947. [PMID: 38956321 PMCID: PMC11286520 DOI: 10.1038/s41565-024-01717-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 06/11/2024] [Indexed: 07/04/2024]
Abstract
The Nernst effect, a transverse thermoelectric phenomenon, has attracted significant attention for its potential in energy conversion, thermoelectrics and spintronics. However, achieving high performance and versatility at low temperatures remains elusive. Here we demonstrate a large and electrically tunable Nernst effect by combining the electrical properties of graphene with the semiconducting characteristics of indium selenide in a field-effect geometry. Our results establish a new platform for exploring and manipulating this thermoelectric effect, showcasing the first electrical tunability with an on/off ratio of 103. Moreover, photovoltage measurements reveal a stronger photo-Nernst signal in the graphene/indium selenide heterostructure compared with individual components. Remarkably, we observe a record-high Nernst coefficient of 66.4 μV K-1 T-1 at ultralow temperatures and low magnetic fields, an important step towards applications in quantum information and low-temperature emergent phenomena.
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Affiliation(s)
- Gabriele Pasquale
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Zhe Sun
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Guilherme Migliato Marega
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Andras Kis
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
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2
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Hu S, Qiao J, Gu G, Xue QK, Zhang D. Vortex entropy and superconducting fluctuations in ultrathin underdoped Bi 2Sr 2CaCu 2O 8+x superconductor. Nat Commun 2024; 15:4818. [PMID: 38844439 PMCID: PMC11156657 DOI: 10.1038/s41467-024-48899-6] [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: 05/22/2023] [Accepted: 05/15/2024] [Indexed: 06/09/2024] Open
Abstract
Vortices in superconductors can help identify emergent phenomena but certain fundamental aspects of vortices, such as their entropy, remain poorly understood. Here, we study the vortex entropy in underdoped Bi2Sr2CaCu2O8+x by measuring both magneto-resistivity and Nernst effect on ultrathin flakes (≤2 unit-cell). We extract the London penetration depth from the magneto-transport measurements on samples with different doping levels. It reveals that the superfluid phase stiffness ρs scales linearly with the superconducting transition temperature Tc, down to the extremely underdoped case. On the same batch of ultrathin flakes, we measure the Nernst effect via on-chip thermometry. Together, we obtain the vortex entropy and find that it decays exponentially with Tc or ρs. We further analyze the Nernst signal above Tc in the framework of Gaussian superconducting fluctuations. The combination of electrical and thermoelectric measurements in the two-dimensional limit provides fresh insight into high temperature superconductivity.
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Affiliation(s)
- Shuxu Hu
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, China
| | - Jiabin Qiao
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, China.
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement, School of Physics, Beijing Institute of Technology, Beijing, China.
- Beijing Academy of Quantum Information Sciences, Beijing, China.
| | - Genda Gu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, USA
| | - Qi-Kun Xue
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, China.
- Beijing Academy of Quantum Information Sciences, Beijing, China.
- Southern University of Science and Technology, Shenzhen, China.
- Frontier Science Center for Quantum Information, Beijing, China.
| | - Ding Zhang
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, China.
- Beijing Academy of Quantum Information Sciences, Beijing, China.
- Frontier Science Center for Quantum Information, Beijing, China.
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama, Japan.
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3
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Mou Y, Chen H, Liu J, Lan Q, Wang J, Zhang C, Wang Y, Gu J, Zhao T, Jiang X, Shi W, Zhang C. Gate-Tunable Quantum Acoustoelectric Transport in Graphene. NANO LETTERS 2024; 24:4625-4632. [PMID: 38568748 DOI: 10.1021/acs.nanolett.4c00774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/05/2024]
Abstract
Transport probes the motion of quasi-particles in response to external excitations. Apart from the well-known electric and thermoelectric transport, acoustoelectric transport induced by traveling acoustic waves has rarely been explored. Here, by adopting hybrid nanodevices integrated with piezoelectric substrates, we establish a simple design of acoustoelectric transport with gate tunability. We fabricate dual-gated acoustoelectric devices based on hBN-encapsulated graphene on LiNbO3. Longitudinal and transverse acoustoelectric voltages are generated by launching a pulsed surface acoustic wave. The gate dependence of zero-field longitudinal acoustoelectric signal presents strikingly similar profiles to that of Hall resistivity, providing a valid approach for extracting carrier density without magnetic field. In magnetic fields, acoustoelectric quantum oscillations appear due to Landau quantization, which are more robust and pronounced than Shubnikov-de Haas oscillations. Our work demonstrates a feasible acoustoelectric setup with gate tunability, which can be extended to the broad scope of various van der Waals materials.
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Affiliation(s)
- Yicheng Mou
- State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Haonan Chen
- State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Jiaqi Liu
- State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Qing Lan
- State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Jiayu Wang
- State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Chuanxin Zhang
- Department of Biomedical Engineering, School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Yuxiang Wang
- State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Jiaming Gu
- State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Tuoyu Zhao
- State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Xue Jiang
- Department of Biomedical Engineering, School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Wu Shi
- State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 201210, China
| | - Cheng Zhang
- State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 201210, China
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4
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Ienaga K, Tamoto Y, Yoda M, Yoshimura Y, Ishigami T, Okuma S. Broadened quantum critical ground state in a disordered superconducting thin film. Nat Commun 2024; 15:2388. [PMID: 38493176 PMCID: PMC10944498 DOI: 10.1038/s41467-024-46628-7] [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: 08/25/2023] [Accepted: 02/29/2024] [Indexed: 03/18/2024] Open
Abstract
A superconductor-insulator transition (SIT) in two dimensions is a prototypical quantum phase transition (QPT) with a clear quantum critical point (QCP) at zero temperature (T = 0). The SIT is induced by a field B and observed in disordered thin films. In some of weakly disordered or crystalline thin films, however, an anomalous metallic (AM) ground state emerges over a wide B range between the superconducting and insulating phases. It remains a fundamental open question how the QPT picture of the SIT is modified when the AM state appears. Here we present measurements of the Nernst effect N, which has great sensitivity to the fluctuations of the superconducting order parameter. From a thorough contour map of N in the B-T plane, we found a thermal-to-quantum crossover line of the superconducting fluctuations, a so-called ghost-temperature line associated with the QPT, as well as a ghost-field line associated with a thermal transition. The QCP is identified as a T = 0 intercept of the ghost-temperature line inside the AM state, which verifies that the AM state is a broadened critical state of the SIT.
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Affiliation(s)
- Koichiro Ienaga
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo, 152-8551, Japan.
| | - Yutaka Tamoto
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Masahiro Yoda
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Yuki Yoshimura
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Takahiro Ishigami
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Satoshi Okuma
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo, 152-8551, Japan
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5
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Homann G, Michael MH, Cosme JG, Mathey L. Dissipationless Counterflow Currents above T_{c} in Bilayer Superconductors. PHYSICAL REVIEW LETTERS 2024; 132:096002. [PMID: 38489633 DOI: 10.1103/physrevlett.132.096002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 02/08/2024] [Indexed: 03/17/2024]
Abstract
We report the existence of dissipationless currents in bilayer superconductors above the critical temperature T_{c}, assuming that the superconducting phase transition is dominated by phase fluctuations. Using a semiclassical U(1) lattice gauge theory, we show that thermal fluctuations cause a transition from the superconducting state at low temperature to a resistive state above T_{c}, accompanied by the proliferation of unbound vortices. Remarkably, while the proliferation of vortex excitations causes dissipation of homogeneous in-plane currents, we find that counterflow currents, flowing in the opposite direction within a bilayer, remain dissipationless. The presence of a dissipationless current channel above T_{c} is attributed to the inhibition of vortex motion by local superconducting coherence within a single bilayer, in the presence of counterflow currents. Our theory presents a possible scenario for the pseudogap phase in bilayer cuprates.
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Affiliation(s)
- Guido Homann
- Zentrum für Optische Quantentechnologien and Institut für Quantenphysik, Universität Hamburg, 22761 Hamburg, Germany
| | - Marios H Michael
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chausse 149, 22761 Hamburg, Germany
| | - Jayson G Cosme
- National Institute of Physics, University of the Philippines, Diliman, Quezon City 1101, Philippines
| | - Ludwig Mathey
- Zentrum für Optische Quantentechnologien and Institut für Quantenphysik, Universität Hamburg, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
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6
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Wu Y, Roy A, Dutta S, Jesudasan J, Raychaudhuri P, Frydman A. Nernst Sign Reversal in the Hexatic Vortex Phase of Weakly Disordered a-MoGe Thin Films. PHYSICAL REVIEW LETTERS 2024; 132:026003. [PMID: 38277584 DOI: 10.1103/physrevlett.132.026003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 09/28/2023] [Accepted: 12/15/2023] [Indexed: 01/28/2024]
Abstract
The hexatic phase is an intermediate stage in the melting process of a 2D crystal due to topological defects. Recently, this exotic phase was experimentally identified in the vortex lattice of 2D weakly disordered superconducting MoGe by scanning tunneling microscopic measurements. Here, we study this vortex state by the Nernst effect, which is an effective and sensitive tool to detect vortex motion, especially in the superconducting fluctuation regime. We find a surprising Nernst sign reversal at the melting transition of the hexatic phase. We propose that they are a consequence of vortex dislocations in the hexatic state which diffuse preferably from the cold to hot.
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Affiliation(s)
- Y Wu
- Department of Physics and Jack and Pearl Resnick Institute and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - A Roy
- Department of Physics and Jack and Pearl Resnick Institute and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
- Department of Physics, Birla Institute of Technology and Science Pilani-K K Birla Goa Campus, Zuarinagar, Goa 403726, India
| | - S Dutta
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - J Jesudasan
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - P Raychaudhuri
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - A Frydman
- Department of Physics and Jack and Pearl Resnick Institute and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
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7
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Hajati Y, Alipourzadeh M, Berakdar J. Magnetoelectric tuning of spin, valley, and layer-resolved anomalous Nernst effect in transition-metal dichalcogenides bilayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:285602. [PMID: 37044101 DOI: 10.1088/1361-648x/accc65] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 04/12/2023] [Indexed: 06/19/2023]
Abstract
The anomalous Nernst coefficient (ANC) for transition-metal dichalcogenide (TMD) bilayers is studied with a focus on the interplay between layer pseudospin, spin, and valley degrees of freedom when electric and exchange fields are present. Breaking the inversion and time reversal symmetries via respectively electric and exchange fields results for bilayer TMDs in a spin-valley-layer polarized total ANC. Conditions are determined for controlling the spin, valley, and layer-resolved contributions via electric field tuning. Our results demonstrate the control of layer degree of freedom in bilayer TMDs magnetoelectrically which is of relevance for possible applications in spin/valley caloritronics.
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Affiliation(s)
- Yaser Hajati
- Institut für Physik, Martin-Luther Universität Halle-Wittenberg, D-06099 Halle, Germany
- Department of Physics, Faculty of Science, Shahid Chamran University of Ahvaz, 6135743135 Ahvaz, Iran
| | - Mohammad Alipourzadeh
- Department of Physics, Faculty of Science, Shahid Chamran University of Ahvaz, 6135743135 Ahvaz, Iran
| | - Jamal Berakdar
- Institut für Physik, Martin-Luther Universität Halle-Wittenberg, D-06099 Halle, Germany
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8
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Spin Seebeck effect mediated reversal of vortex-Nernst effect in superconductor-ferromagnet bilayers. Sci Rep 2023; 13:4425. [PMID: 36932146 PMCID: PMC10023796 DOI: 10.1038/s41598-023-31420-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 03/11/2023] [Indexed: 03/19/2023] Open
Abstract
We report on the observation of sign reversal of vortex-Nernst effect in epitaxial NbN/Fe bilayers deposited on MgO (001) substrates. Strong coupling between vortex magnetisation and ferromagnetic magnetisation at the NbN/Fe bilayer interface is presented. In NbN/Fe bilayer thin films an apparent sign reversal of vortex-Nernst signal under a temperature gradient with magnetic field and temperature is observed when the thickness of Fe is increased up to 5 nm. This reversal of the vortex-Nernst effect is associated with the enhancement of the spin Seebeck effects (SSE) near Tc due to coherence peak effect (CPE) and strong coupling of vortex magnetisation and ferromagnetic magnetisation at the interface of the NbN/Fe bilayer. The observed large SSE via inverse spin Hall effect (ISHE) is due to the CPE below and close to TC, highlighting the high spin to charge conversion efficiency of NbN in this region. This work may contribute to the development of superconducting spintronic devices by engineering the coupling of the superconductor/ferromagnet interface.
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9
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Singh A, Huang HY, Xie JD, Okamoto J, Chen CT, Watanabe T, Fujimori A, Imada M, Huang DJ. Unconventional exciton evolution from the pseudogap to superconducting phases in cuprates. Nat Commun 2022; 13:7906. [PMID: 36550120 PMCID: PMC9780265 DOI: 10.1038/s41467-022-35210-8] [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: 12/09/2021] [Accepted: 11/18/2022] [Indexed: 12/24/2022] Open
Abstract
Electron quasiparticles play a crucial role in simplifying the description of many-body physics in solids with surprising success. Conventional Landau's Fermi-liquid and quasiparticle theories for high-temperature superconducting cuprates have, however, received skepticism from various angles. A path-breaking framework of electron fractionalization has been established to replace the Fermi-liquid theory for systems that show the fractional quantum Hall effect and the Mott insulating phenomena; whether it captures the essential physics of the pseudogap and superconducting phases of cuprates is still an open issue. Here, we show that excitonic excitation of optimally doped Bi2Sr2CaCu2O8+δ with energy far above the superconducting-gap energy scale, about 1 eV or even higher, is unusually enhanced by the onset of superconductivity. Our finding proves the involvement of such high-energy excitons in superconductivity. Therefore, the observed enhancement in the spectral weight of excitons imposes a crucial constraint on theories for the pseudogap and superconducting mechanisms. A simple two-component fermion model which embodies electron fractionalization in the pseudogap state provides a possible mechanism of this enhancement, pointing toward a novel route for understanding the electronic structure of superconducting cuprates.
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Affiliation(s)
- A Singh
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - H Y Huang
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - J D Xie
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, 30093, Taiwan
| | - J Okamoto
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - C T Chen
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - T Watanabe
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, 036-8561, Japan
| | - A Fujimori
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan.
- Center for Quantum Science and Technology and Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan.
- Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
| | - M Imada
- Research Institute for Science and Engineering, Waseda University, Shinjuku, Tokyo, 169-8555, Japan.
- Toyota Physical and Chemical Research Institute, Nagakute, Aichi, 480-1192, Japan.
| | - D J Huang
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan.
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, 30093, Taiwan.
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan.
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10
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Behnia K. Nernst response, viscosity and mobile entropy in vortex liquids. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 35:074003. [PMID: 36541498 DOI: 10.1088/1361-648x/aca9b0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 12/07/2022] [Indexed: 06/17/2023]
Abstract
In a liquid of superconducting vortices, a longitudinal thermal gradient generates a transverse electric field. This Nernst signal peaks at an intermediate temperature and magnetic field, presumably where the entropy difference between the vortex core and the superfluid environment is largest. There is a puzzling similarity of the amplitude of this peak across many different superconductors. This peak can be assimilated to a minimum in the viscosity to entropy density ratio of the vortex liquid. Expressed in units ofℏkB, this minimum is one order of magnitude larger than what is seen in common liquids. Moreover, the entropy stocked in the vortex core isnotidentical to the entropy bound to a moving magnetic flux line. Due to a steady exchange of normal quasi-particles, entropy can leak from the vortex core. A slowly moving vortex will be peeled off its entropy within a distance of the order of a superconducting coherence length, provided that theΔEFratio is sufficiently large.
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Affiliation(s)
- Kamran Behnia
- Laboratoire de Physique et Etude des Matériaux (CNRS- Sorbonne Université), ESPCI Paris, PSL University, 75005 Paris, France
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11
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Little-Parks like oscillations in lightly doped cuprate superconductors. Nat Commun 2022; 13:1316. [PMID: 35288555 PMCID: PMC8921203 DOI: 10.1038/s41467-022-28954-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 02/13/2022] [Indexed: 11/08/2022] Open
Abstract
Understanding the rich and competing electronic orders in cuprate superconductors may provide important insight into the mechanism of high-temperature superconductivity. Here, by measuring Bi2Sr2CaCu2O8+x in the extremely underdoped regime, we obtain evidence for a distinct type of ordering, which manifests itself as resistance oscillations at low magnetic fields (≤10 T) and at temperatures around the superconducting transition. By tuning the doping level p continuously, we reveal that these low-field oscillations occur only when p < 0.1. The oscillation amplitude increases with decreasing p but the oscillation period stays almost constant. We show that these low-field oscillations can be well described by assuming a periodic superconducting structure with a mesh size of about 50 nm. Such a charge order, which is distinctly different from the well-established charge density wave and pair density wave, seems to be an unexpected piece of the puzzle on the correlated physics in cuprates. Understanding the rich electronic orders in cuprate superconductors provide insights into the mechanism of high-temperature superconductivity. Here, the authors report a distinct charge order with Little-Parks like resistance oscillations at magnetic fields up to 10 T and around Tc in lightly doped Bi2Sr2CaCu2O8+x.
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12
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Raychaudhuri P, Dutta S. Phase fluctuations in conventional superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:083001. [PMID: 34731851 DOI: 10.1088/1361-648x/ac360b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 11/03/2021] [Indexed: 06/13/2023]
Abstract
Within the Bardeen-Cooper-Schrieffer (BCS) theory, superconductivity is entirely governed by the pairing energy scale, which gives rise to the superconducting energy gap, Δ. However, another important energy scale, the superfluid phase stiffness,J, which determines the resilience of the superconductor to phase-fluctuations is normally ignored. The spectacular success of BCS theory owes to the fact that in conventional superconductorsJis normally several orders of magnitude larger than Δ and thus an irrelevant energy scale. However, in certain situations such as in the presence of low carrier density, strong disorder, at low-dimensions or in granular superconductors,Jcan drastically come down and even become smaller than Δ. In such situations, the temperature and magnetic field evolution of superconducting properties is governed by phase fluctuations, which gives rise to novel electronic states where signatures of electronic pairing continue to exist even when the zero resistance state is destroyed. In this article, we will review the recent experimental developments on the study of phase fluctuations in conventional superconductors.
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Affiliation(s)
- Pratap Raychaudhuri
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Surajit Dutta
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
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13
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Zong A, Dolgirev PE, Kogar A, Su Y, Shen X, Straquadine JAW, Wang X, Luo D, Kozina ME, Reid AH, Li R, Yang J, Weathersby SP, Park S, Sie EJ, Jarillo-Herrero P, Fisher IR, Wang X, Demler E, Gedik N. Role of Equilibrium Fluctuations in Light-Induced Order. PHYSICAL REVIEW LETTERS 2021; 127:227401. [PMID: 34889631 DOI: 10.1103/physrevlett.127.227401] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 10/01/2021] [Indexed: 06/13/2023]
Abstract
Engineering novel states of matter with light is at the forefront of materials research. An intensely studied direction is to realize broken-symmetry phases that are "hidden" under equilibrium conditions but can be unleashed by an ultrashort laser pulse. Despite a plethora of experimental discoveries, the nature of these orders and how they transiently appear remain unclear. To this end, we investigate a nonequilibrium charge density wave (CDW) in rare-earth tritellurides, which is suppressed in equilibrium but emerges after photoexcitation. Using a pump-pump-probe protocol implemented in ultrafast electron diffraction, we demonstrate that the light-induced CDW consists solely of order parameter fluctuations, which bear striking similarities to critical fluctuations in equilibrium despite differences in the length scale. By calculating the dynamics of CDW fluctuations in a nonperturbative model, we further show that the strength of the light-induced order is governed by the amplitude of equilibrium fluctuations. These findings highlight photoinduced fluctuations as an important ingredient for the emergence of transient orders out of equilibrium. Our results further suggest that materials with strong fluctuations in equilibrium are promising platforms to host hidden orders after laser excitation.
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Affiliation(s)
- Alfred Zong
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Chemistry, University of California at Berkeley, Berkeley, California 94720, USA
| | - Pavel E Dolgirev
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Anshul Kogar
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, California 90095, USA
| | - Yifan Su
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Xiaozhe Shen
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Joshua A W Straquadine
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Xirui Wang
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Duan Luo
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Michael E Kozina
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Alexander H Reid
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Renkai Li
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Jie Yang
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | | | - Suji Park
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - Edbert J Sie
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Pablo Jarillo-Herrero
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Ian R Fisher
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Xijie Wang
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Eugene Demler
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - Nuh Gedik
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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14
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Possible Evidence for Berezinskii-Kosterlitz-Thouless Transition in Ba(Fe 0.914Co 0.086) 2As 2 Crystals. MATERIALS 2021; 14:ma14216294. [PMID: 34771819 PMCID: PMC8585216 DOI: 10.3390/ma14216294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/11/2021] [Accepted: 10/16/2021] [Indexed: 11/24/2022]
Abstract
In this study, we measure the in-plane transport properties of high-quality Ba(Fe0.914Co0.086)2As2 single crystals. Signatures of vortex unbinding Berezinskii–Kosterlitz–Thouless (BKT) transition are shown from both the conventional approach and the Fisher–Fisher–Huse dynamic scaling analysis, in which a characteristic Nelson–Kosterlitz jump is demonstrated. We also observe a non-Hall transverse signal exactly at the superconducting transition, which is explained in terms of guided motion of unbound vortices.
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15
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Wang S, Choubey P, Chong YX, Chen W, Ren W, Eisaki H, Uchida S, Hirschfeld PJ, Davis JCS. Scattering interference signature of a pair density wave state in the cuprate pseudogap phase. Nat Commun 2021; 12:6087. [PMID: 34667154 PMCID: PMC8526682 DOI: 10.1038/s41467-021-26028-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 09/09/2021] [Indexed: 11/21/2022] Open
Abstract
An unidentified quantum fluid designated the pseudogap (PG) phase is produced by electron-density depletion in the CuO2 antiferromagnetic insulator. Current theories suggest that the PG phase may be a pair density wave (PDW) state characterized by a spatially modulating density of electron pairs. Such a state should exhibit a periodically modulating energy gap [Formula: see text] in real-space, and a characteristic quasiparticle scattering interference (QPI) signature [Formula: see text] in wavevector space. By studying strongly underdoped Bi2Sr2CaDyCu2O8 at hole-density ~0.08 in the superconductive phase, we detect the 8a0-periodic [Formula: see text] modulations signifying a PDW coexisting with superconductivity. Then, by visualizing the temperature dependence of this electronic structure from the superconducting into the pseudogap phase, we find the evolution of the scattering interference signature [Formula: see text] that is predicted specifically for the temperature dependence of an 8a0-periodic PDW. These observations are consistent with theory for the transition from a PDW state coexisting with d-wave superconductivity to a pure PDW state in the Bi2Sr2CaDyCu2O8 pseudogap phase.
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Affiliation(s)
- Shuqiu Wang
- Clarendon Laboratory, University of Oxford, Oxford, UK
| | - Peayush Choubey
- Institut für Theoretische Physik III, Ruhr-Universität Bochum, Bochum, Germany
- Department of Physics, Indian Institute of Technology (Indian School of Mines), Dhanbad, Jharkhand, India
| | - Yi Xue Chong
- LASSP, Department of Physics, Cornell University, Ithaca, NY, USA
| | - Weijiong Chen
- Clarendon Laboratory, University of Oxford, Oxford, UK
| | - Wangping Ren
- Clarendon Laboratory, University of Oxford, Oxford, UK
| | - H Eisaki
- Institute of Advanced Industrial Science and Tech., Tsukuba, Ibaraki, Japan
| | - S Uchida
- Institute of Advanced Industrial Science and Tech., Tsukuba, Ibaraki, Japan
| | | | - J C Séamus Davis
- Clarendon Laboratory, University of Oxford, Oxford, UK.
- LASSP, Department of Physics, Cornell University, Ithaca, NY, USA.
- Department of Physics, University College Cork, Cork, Ireland.
- Max-Planck Institute for Chemical Physics of Solids, Dresden, Germany.
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16
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Zaytseva I, Abaloszew A, Camargo BC, Syryanyy Y, Cieplak MZ. Upper critical field and superconductor-metal transition in ultrathin niobium films. Sci Rep 2020; 10:19062. [PMID: 33149161 PMCID: PMC7642399 DOI: 10.1038/s41598-020-75968-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 10/20/2020] [Indexed: 11/09/2022] Open
Abstract
Recent studies suggest that in disordered ultrathin films superconducting (SC) state may be intrinsically inhomogeneous. Here we investigate the nature of SC state in ultrathin Nb films, of thickness d ranging from 1.2 to 20 nm, which undergo a transition from amorphous to polycrystalline structure at the thickness [Formula: see text] nm. We show that the properties of SC state are very different in polycrystalline and amorphous films. The upper critical field ([Formula: see text]) is orbitally limited in the first case, and paramagnetically limited in the latter. The magnetic field induced superconductor-metal transition is observed, with the critical field approximately constant or decreasing as a power-law with the film conductance in polycrystalline or amorphous films, respectively. The scaling analysis indicates distinct scaling exponents in these two types of films. Negative contribution of the SC fluctuations to conductivity exists above [Formula: see text], particularly pronounced in amorphous films, signaling the presence of fluctuating Cooper pairs. These observations suggest the development of local inhomogeneities in the amorphous films, in the form of proximity-coupled SC islands. An usual evolution of SC correlations on cooling is observed in amorphous films, likely related to the effect of quantum fluctuations on the proximity-induced phase coherence.
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Affiliation(s)
- Iryna Zaytseva
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02668, Warsaw, Poland.
| | - Aleksander Abaloszew
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02668, Warsaw, Poland
| | - Bruno C Camargo
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02668, Warsaw, Poland
| | - Yevgen Syryanyy
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02668, Warsaw, Poland
| | - Marta Z Cieplak
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02668, Warsaw, Poland.
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17
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Chu H, Kim MJ, Katsumi K, Kovalev S, Dawson RD, Schwarz L, Yoshikawa N, Kim G, Putzky D, Li ZZ, Raffy H, Germanskiy S, Deinert JC, Awari N, Ilyakov I, Green B, Chen M, Bawatna M, Cristiani G, Logvenov G, Gallais Y, Boris AV, Keimer B, Schnyder AP, Manske D, Gensch M, Wang Z, Shimano R, Kaiser S. Phase-resolved Higgs response in superconducting cuprates. Nat Commun 2020; 11:1793. [PMID: 32286291 PMCID: PMC7156672 DOI: 10.1038/s41467-020-15613-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 03/02/2020] [Indexed: 11/29/2022] Open
Abstract
In high-energy physics, the Higgs field couples to gauge bosons and fermions and gives mass to their elementary excitations. Experimentally, such couplings can be inferred from the decay product of the Higgs boson, i.e., the scalar (amplitude) excitation of the Higgs field. In superconductors, Cooper pairs bear a close analogy to the Higgs field. Interaction between the Cooper pairs and other degrees of freedom provides dissipation channels for the amplitude mode, which may reveal important information about the microscopic pairing mechanism. To this end, we investigate the Higgs (amplitude) mode of several cuprate thin films using phase-resolved terahertz third harmonic generation (THG). In addition to the heavily damped Higgs mode itself, we observe a universal jump in the phase of the driven Higgs oscillation as well as a non-vanishing THG above Tc. These findings indicate coupling of the Higgs mode to other collective modes and potentially a nonzero pairing amplitude above Tc. Interaction between Cooper pairs and other collective excitations may reveal important information about the pairing mechanism. Here, the authors observe a universal jump in the phase of the driven Higgs oscillations in cuprate thin films, indicating the presence of a coupled collective mode, as well as a nonvanishing Higgs-like response at high temperatures, suggesting a potential nonzero pairing amplitude above Tc.
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Affiliation(s)
- Hao Chu
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany.,4th Physics Institute, University of Stuttgart, 70569, Stuttgart, Germany.,Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Min-Jae Kim
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany.,4th Physics Institute, University of Stuttgart, 70569, Stuttgart, Germany
| | - Kota Katsumi
- Department of Physics, University of Tokyo, Hongo, Tokyo, 113-0033, Japan
| | - Sergey Kovalev
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany
| | - Robert David Dawson
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Lukas Schwarz
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Naotaka Yoshikawa
- Department of Physics, University of Tokyo, Hongo, Tokyo, 113-0033, Japan
| | - Gideok Kim
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Daniel Putzky
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Zhi Zhong Li
- Laboratoire de Physique des Solides (CNRS UMR 8502), Bâtiment 510, Université Paris-Saclay, 91405, Orsay, France
| | - Hélène Raffy
- Laboratoire de Physique des Solides (CNRS UMR 8502), Bâtiment 510, Université Paris-Saclay, 91405, Orsay, France
| | - Semyon Germanskiy
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany
| | - Jan-Christoph Deinert
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany
| | - Nilesh Awari
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany.,University of Groningen, 9747 AG, Groningen, Netherlands
| | - Igor Ilyakov
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany
| | - Bertram Green
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany
| | - Min Chen
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany.,Technische Universität Berlin, Institut für Optik und Atomare Physik, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Mohammed Bawatna
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany
| | - Georg Cristiani
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Gennady Logvenov
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Yann Gallais
- Laboratoire Matériaux et Phénomènes Quantiques (UMR 7162 CNRS), Université de Paris, Bâtiment Condorcet, 75205, Paris Cedex 13, France
| | - Alexander V Boris
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Bernhard Keimer
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Andreas P Schnyder
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Dirk Manske
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Michael Gensch
- Technische Universität Berlin, Institut für Optik und Atomare Physik, Strasse des 17. Juni 135, 10623, Berlin, Germany.,German Aerospace Center (DLR), Institute of Optical Sensor Systems, Rutherfordstrasse 2, 12489, Berlin, Germany
| | - Zhe Wang
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany. .,Institute of Physics II, University of Cologne, 50937, Cologne, Germany.
| | - Ryo Shimano
- Department of Physics, University of Tokyo, Hongo, Tokyo, 113-0033, Japan. .,Cryogenic Research Center, University of Tokyo, Hongo, Tokyo, 113-0032, Japan.
| | - Stefan Kaiser
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany. .,4th Physics Institute, University of Stuttgart, 70569, Stuttgart, Germany.
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18
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Mallik AV, Gupta GK, Shenoy VB, Krishnamurthy HR. Surprises in the t-J Model: Implications for Cuprates. PHYSICAL REVIEW LETTERS 2020; 124:147002. [PMID: 32338957 DOI: 10.1103/physrevlett.124.147002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 02/09/2020] [Accepted: 03/16/2020] [Indexed: 06/11/2023]
Abstract
Many strongly correlated systems, such as the cuprate superconductors, have the interesting physics of low dimensionality and hence enhanced fluctuation effects. We perform an analysis of the t-J model in the slave boson formulation which accounts for strong correlations, focusing on fluctuation effects that have hitherto not received the attention they deserve. We find several interesting results including the instability of the d-wave superconducting state to internal phase fluctuations giving way to a time reversal broken d+is^{*} superconductor at low doping. This offers an explanation for some recent experimental findings in the cuprate superconductors, including the observation of nodeless superconductivity at low doping. We also suggest further experiments that can validate our claims. On a broader perspective, this work points to the importance of considering fluctuation effects in other two-dimensional strongly correlated systems opening up a plethora of possibilities.
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Affiliation(s)
- Aabhaas V Mallik
- Department of Physics, Center for Condensed Matter Theory, Indian Institute of Science, Bengaluru 560012, India
| | - Gaurav K Gupta
- Department of Physics, Center for Condensed Matter Theory, Indian Institute of Science, Bengaluru 560012, India
| | - Vijay B Shenoy
- Department of Physics, Center for Condensed Matter Theory, Indian Institute of Science, Bengaluru 560012, India
| | - H R Krishnamurthy
- Department of Physics, Center for Condensed Matter Theory, Indian Institute of Science, Bengaluru 560012, India
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19
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Kavokin AV, Altshuler BL, Sharapov SG, Grigoryev PS, Varlamov AA. The Nernst effect in Corbino geometry. Proc Natl Acad Sci U S A 2020; 117:2846-2851. [PMID: 31992642 PMCID: PMC7022160 DOI: 10.1073/pnas.1916567117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We study the manifestation of the Nernst effect in the Corbino disk subjected to the normal external magnetic field and to the radial temperature gradient. The Corbino geometry offers a precious opportunity for the direct measurement of the magnetization currents that are masked by kinetic contributions to the Nernst current in the conventional geometry. The magnetization currents, also referred to as the edge currents, are independent on the conductivity of the sample which is why they can be conveniently described within the thermodynamic approach. They can be related to the Landau thermodynamic potential for an infinite system. We demonstrate that the observable manifestation of this, purely thermodynamic, Nernst effect consists in the strong oscillations of the magnetic field measured in the center of the disk as a function of the external field. The oscillations depend on the temperature difference at the edges of the disk. Dirac fermions and 2D electrons with a parabolic spectrum are characterized by oscillations of different phase and frequency. We predict qualitatively different power dependencies of the magnitude of the Nernst signal on the chemical potential for normal and Dirac carriers.
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Affiliation(s)
- A V Kavokin
- Westlake University, Hangzhou 310024, Zhejiang Province, China;
| | - B L Altshuler
- Westlake University, Hangzhou 310024, Zhejiang Province, China;
- Department of Physics, Columbia University, New York, NY 10027
| | - S G Sharapov
- Bogolyubov Institute for Theoretical Physics, National Academy of Science of Ukraine, Kyiv 03680, Ukraine
| | - P S Grigoryev
- Spin Optics Laboratory, St. Petersburg State University, 198504 St. Petersburg, Russia
| | - A A Varlamov
- Consiglio Nazionale delle Ricerche-Superconducting and Other Innovative Materials and Devices Institute (CNR-SPIN), DICII-Universitá di Roma Tor Vergata, I-00133 Roma, Italy
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20
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Robinson NJ, Johnson PD, Rice TM, Tsvelik AM. Anomalies in the pseudogap phase of the cuprates: competing ground states and the role of umklapp scattering. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2019; 82:126501. [PMID: 31300626 DOI: 10.1088/1361-6633/ab31ed] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Over the past two decades, advances in computational algorithms have revealed a curious property of the two-dimensional Hubbard model (and related theories) with hole doping: the presence of close-in-energy competing ground states that display very different physical properties. On the one hand, there is a complicated state exhibiting intertwined spin, charge, and pair density wave orders. We call this 'type A'. On the other hand, there is a uniform d-wave superconducting state that we denote as 'type B'. We advocate, with the support of both microscopic theoretical calculations and experimental data, dividing the high-temperature cuprate superconductors into two corresponding families, whose properties reflect either the type A or type B ground states at low temperatures. We review the anomalous properties of the pseudogap phase that led us to this picture, and present a modern perspective on the role that umklapp scattering plays in these phenomena in the type B materials. This reflects a consistent framework that has emerged over the last decade, in which Mott correlations at weak coupling drive the formation of the pseudogap. We discuss this development, recent theory and experiments, and open issues.
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Affiliation(s)
- Neil J Robinson
- Institute for Theoretical Physics, University of Amsterdam, Science Park 904, Postbus 94485, 1098 XH Amsterdam, The Netherlands
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21
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Zhao SYF, Poccia N, Panetta MG, Yu C, Johnson JW, Yoo H, Zhong R, Gu GD, Watanabe K, Taniguchi T, Postolova SV, Vinokur VM, Kim P. Sign-Reversing Hall Effect in Atomically Thin High-Temperature Bi_{2.1}Sr_{1.9}CaCu_{2.0}O_{8+δ} Superconductors. PHYSICAL REVIEW LETTERS 2019; 122:247001. [PMID: 31322397 DOI: 10.1103/physrevlett.122.247001] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 01/31/2019] [Indexed: 06/10/2023]
Abstract
We developed novel techniques to fabricate atomically thin Bi_{2.1}Sr_{1.9}CaCu_{2.0}O_{8+δ} van der Waals heterostructures down to two unit cells while maintaining a transition temperature T_{c} close to the bulk, and carry out magnetotransport measurements on these van der Waals devices. We find a double sign change of the Hall resistance R_{xy} as in the bulk system, spanning both below and above T_{c}. Further, we observe a drastic enlargement of the region of sign reversal in the temperature-magnetic field phase diagram with decreasing thickness of the device. We obtain quantitative agreement between experimental R_{xy}(T,B) and the predictions of the vortex dynamics-based description of Hall effect in high-temperature superconductors both above and below T_{c}.
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Affiliation(s)
- S Y Frank Zhao
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Nicola Poccia
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Margaret G Panetta
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Cyndia Yu
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Jedediah W Johnson
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Hyobin Yoo
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Ruidan Zhong
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - G D Gu
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Kenji Watanabe
- National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan
| | - Svetlana V Postolova
- Institute for Physics of Microstructures RAS, Nizhny Novgorod 603950, Russia
- Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090, Russia
| | - Valerii M Vinokur
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
- Consortium for Advanced Science and Engineering, Office of Research and National Laboratories, University of Chicago, Chicago, Illinois 60637, USA
| | - Philip Kim
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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22
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Tu WL, Lee TK. Evolution of Pairing Orders between Pseudogap and Superconducting Phases of Cuprate Superconductors. Sci Rep 2019; 9:1719. [PMID: 30737472 PMCID: PMC6368576 DOI: 10.1038/s41598-018-38288-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 12/10/2018] [Indexed: 11/09/2022] Open
Abstract
One of the most puzzling problems of high temperature cuprate superconductor is the pseudogap phase (PG) at temperatures above the superconducting transition temperature in the underdoped regime. The PG phase is found by the angle-resolved photoemission spectra (ARPES) to have a gap at some regions in momentum space and a fraction of Fermi surface remained, known as Fermi arcs. The arc turns into a d-wave SC gap with a node below the SC transition temperature. Here, by studying a strongly correlated model at low temperatures, we obtained a phase characterized by two kinds of pairing order parameters with the total momentum of the Cooper pair to be zero and finite. The finite momentum pairing is accompanied with a spatial modulation of pairing order, i.e. a pair density wave (PDW). These PDW phases are intertwined with modulations of charge density and intra-unit cell form factors. The coexistence of the two different pairing orders provides the unique two-gaps like spectra observed by ARPES for superconducting cuprates. As temperature raises, the zero-momentum pairing order vanishes while the finite momentum pairing orders are kept, thus Fermi arcs are realized. The calculated quasiparticle spectra have the similar doping and temperature dependence as reported by ARPES and scanning tunneling spectroscopy (STS). The consequence of breaking symmetry between x and y due to the unidirectional PDW and the possibility to probe such a PDW state in the PG phase is discussed.
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Affiliation(s)
- Wei-Lin Tu
- Department of Physics, National Taiwan University, Daan, Taipei, 10617, Taiwan
- Laboratoire de Physique Théorique, IRSAMC, Université de Toulouse, CNRS, UPS, Toulouse, France
- 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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23
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Zhou X, Peets DC, Morgan B, Huttema WA, Murphy NC, Thewalt E, Truncik CJS, Turner PJ, Koenig AJ, Waldram JR, Hosseini A, Liang R, Bonn DA, Hardy WN, Broun DM. Logarithmic Upturn in Low-Temperature Electronic Transport as a Signature of d-Wave Order in Cuprate Superconductors. PHYSICAL REVIEW LETTERS 2018; 121:267004. [PMID: 30636125 DOI: 10.1103/physrevlett.121.267004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 09/13/2018] [Indexed: 06/09/2023]
Abstract
In cuprate superconductors, high magnetic fields have been used extensively to suppress superconductivity and expose the underlying normal state. Early measurements revealed insulatinglike behavior in underdoped material versus temperature T, in which resistivity increases on cooling with a puzzling log(1/T) form. We instead use microwave measurements of flux-flow resistivity in YBa_{2}Cu_{3}O_{6+y} and Tl_{2}Ba_{2}CuO_{6+δ} to study charge transport deep inside the superconducting phase, in the low-temperature and low-field regime. Here, the transition from metallic low-temperature resistivity (dρ/dT>0) to a log(1/T) upturn persists throughout the superconducting doping range, including a regime at high carrier dopings in which the field-revealed normal-state resistivity is Fermi-liquid-like. The log(1/T) form is thus likely a signature of d-wave superconducting order, and the field-revealed normal state's log(1/T) resistivity may indicate the free-flux-flow regime of a phase-disordered d-wave superconductor.
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Affiliation(s)
- Xiaoqing Zhou
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
- Department of Physics, University of Colorado, Boulder, Colorado 80309-0390, USA
| | - D C Peets
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200438, People's Republic of China
| | - Benjamin Morgan
- Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, United Kingdom
| | - W A Huttema
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - N C Murphy
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - E Thewalt
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - C J S Truncik
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - P J Turner
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - A J Koenig
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - J R Waldram
- Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, United Kingdom
| | - A Hosseini
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Ruixing Liang
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Canadian Institute for Advanced Research, Toronto, Ontario MG5 1Z8, Canada
| | - D A Bonn
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Canadian Institute for Advanced Research, Toronto, Ontario MG5 1Z8, Canada
| | - W N Hardy
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Canadian Institute for Advanced Research, Toronto, Ontario MG5 1Z8, Canada
| | - D M Broun
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
- Canadian Institute for Advanced Research, Toronto, Ontario MG5 1Z8, Canada
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24
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Pelc D, Vučković M, Grbić MS, Požek M, Yu G, Sasagawa T, Greven M, Barišić N. Emergence of superconductivity in the cuprates via a universal percolation process. Nat Commun 2018; 9:4327. [PMID: 30337539 PMCID: PMC6193991 DOI: 10.1038/s41467-018-06707-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 09/07/2018] [Indexed: 11/09/2022] Open
Abstract
A pivotal step toward understanding unconventional superconductors would be to decipher how superconductivity emerges from the unusual normal state. In the cuprates, traces of superconducting pairing appear above the macroscopic transition temperature Tc, yet extensive investigation has led to disparate conclusions. The main difficulty has been to separate superconducting contributions from complex normal-state behaviour. Here we avoid this problem by measuring nonlinear conductivity, an observable that is zero in the normal state. We uncover for several representative cuprates that the nonlinear conductivity vanishes exponentially above Tc, both with temperature and magnetic field, and exhibits temperature-scaling characterized by a universal scale Ξ0. Attempts to model the response with standard Ginzburg-Landau theory are systematically unsuccessful. Instead, our findings are captured by a simple percolation model that also explains other properties of the cuprates. We thus resolve a long-standing conundrum by showing that the superconducting precursor in the cuprates is strongly affected by intrinsic inhomogeneity.
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Affiliation(s)
- Damjan Pelc
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička 32, HR-10000, Zagreb, Croatia
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Marija Vučković
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička 32, HR-10000, Zagreb, Croatia
- University Hospital Centre Zagreb, Kišpatićeva 12, HR-10000, Zagreb, Croatia
| | - Mihael S Grbić
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička 32, HR-10000, Zagreb, Croatia
| | - Miroslav Požek
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička 32, HR-10000, Zagreb, Croatia.
| | - Guichuan Yu
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Takao Sasagawa
- Materials and Structures Laboratory, Tokyo Institute of Technology, Kanagawa, 226-8503, Japan
| | - Martin Greven
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA.
| | - Neven Barišić
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA.
- Institute of Solid State Physics, TU Wien, 1040, Vienna, Austria.
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25
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Shiomi Y, Lustikova J, Saitoh E. Oscillatory Nernst effect in Pt|ferrite|cuprate-superconductor trilayer films. Sci Rep 2017; 7:5358. [PMID: 28706217 PMCID: PMC5509755 DOI: 10.1038/s41598-017-05747-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 04/26/2017] [Indexed: 11/25/2022] Open
Abstract
Although magnetism and superconductivity hardly coexist in a single material, recent advances in nanotechnology and spintronics have brought to light their interplay in magnetotransport in thin-film heterostructures. Here, we found a periodic oscillation of Nernst voltage with respect to magnetic fields in Pt|LiFe5O8 (Pt|LFO) bilayers grown on a cuprate superconductor YBa2Cu3O7−x (YBCO). At high temperatures above the superconducting transition temperature (TC) of YBCO, spin Seebeck voltages originating in Pt|LFO layers are observed. As temperature decreases well below TC, the spin Seebeck voltage is suppressed and unconventional periodic voltage oscillation as a function of magnetic fields appears; such an oscillation emerging along the Hall direction in the superconducting state has not been observed yet. Dynamics of superconducting vortices pinned by surface precipitates seems responsible for the oscillatory Nernst effect.
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Affiliation(s)
- Y Shiomi
- Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan. .,Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Aoba-ku, Sendai, 980-8577, Japan.
| | - J Lustikova
- Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - E Saitoh
- Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Aoba-ku, Sendai, 980-8577, Japan.,WPI Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, 319-1195, Japan
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26
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Chan MK, Tang Y, Dorow CJ, Jeong J, Mangin-Thro L, Veit MJ, Ge Y, Abernathy DL, Sidis Y, Bourges P, Greven M. Hourglass Dispersion and Resonance of Magnetic Excitations in the Superconducting State of the Single-Layer Cuprate HgBa_{2}CuO_{4+δ} Near Optimal Doping. PHYSICAL REVIEW LETTERS 2016; 117:277002. [PMID: 28084762 DOI: 10.1103/physrevlett.117.277002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Indexed: 06/06/2023]
Abstract
We use neutron scattering to study magnetic excitations near the antiferromagnetic wave vector in the underdoped single-layer cuprate HgBa_{2}CuO_{4+δ} (superconducting transition temperature T_{c}≈88 K, pseudogap temperature T^{*}≈220 K). The response is distinctly enhanced below T^{*} and exhibits a Y-shaped dispersion in the pseudogap state, whereas the superconducting state features an X-shaped (hourglass) dispersion and a further resonancelike enhancement. A large spin gap of about 40 meV is observed in both states. This phenomenology is reminiscent of that exhibited by bilayer cuprates. The resonance spectral weight, irrespective of doping and compound, scales linearly with the putative binding energy of a spin exciton described by an itinerant-spin formalism.
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Affiliation(s)
- M K Chan
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
- Pulsed Field Facility, National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Y Tang
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - C J Dorow
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - J Jeong
- Laboratoire Léon Brillouin, CEA-CNRS, CEA-Saclay, 91191 Gif sur Yvette, France
| | - L Mangin-Thro
- Laboratoire Léon Brillouin, CEA-CNRS, CEA-Saclay, 91191 Gif sur Yvette, France
| | - M J Veit
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Y Ge
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - D L Abernathy
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Y Sidis
- Laboratoire Léon Brillouin, CEA-CNRS, CEA-Saclay, 91191 Gif sur Yvette, France
| | - P Bourges
- Laboratoire Léon Brillouin, CEA-CNRS, CEA-Saclay, 91191 Gif sur Yvette, France
| | - M Greven
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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27
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Xiao H, Gao B, Ma YH, Li XJ, Mu G, Hu T. Superconducting fluctuation effect in CaFe0.88Co0.12AsF. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:455701. [PMID: 27619794 DOI: 10.1088/0953-8984/28/45/455701] [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
Out-of-plane angular dependent torque measurements were performed on CaFe0.88Co0.12AsF single crystals. Superconducting fluctuations, featured by magnetic field enhanced and exponential temperature dependent diamagnetism, are observed above the superconducting transition temperature T c, which is similar to that of cuprate superconductors, but less pronounced. In addition, the ratio of T c versus superfluid density follows well the Uemura line of high-T c cuprates, which suggests the exotic nature of the superconductivity in CaFe0.88Co0.12AsF.
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Affiliation(s)
- H Xiao
- Center for High Pressure Science and Technology Advanced Research, Beijing, 100094, People's Republic of China
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28
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Ziabari A, Zebarjadi M, Vashaee D, Shakouri A. Nanoscale solid-state cooling: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:095901. [PMID: 27519021 DOI: 10.1088/0034-4885/79/9/095901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The recent developments in nanoscale solid-state cooling are reviewed. This includes both theoretical and experimental studies of different physical concepts, as well as nanostructured material design and device configurations. We primarily focus on thermoelectric, thermionic and thermo-magnetic coolers. Particular emphasis is given to the concepts based on metal-semiconductor superlattices, graded materials, non-equilibrium thermoelectric devices, Thomson coolers, and photon assisted Peltier coolers as promising methods for efficient solid-state cooling. Thermomagnetic effects such as magneto-Peltier and Nernst-Ettingshausen cooling are briefly described and recent advances and future trends in these areas are reviewed. The ongoing progress in solid-state cooling concepts such as spin-calorimetrics, electrocalorics, non-equilibrium/nonlinear Peltier devices, superconducting junctions and two-dimensional materials are also elucidated and practical achievements are reviewed. We explain the thermoreflectance thermal imaging microscopy and the transient Harman method as two unique techniques developed for characterization of thermoelectric microrefrigerators. The future prospects for solid-state cooling are briefly summarized.
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Affiliation(s)
- Amirkoushyar Ziabari
- Birck Nanotechnology Center and Electrical and Computer Engineering, Purdue University, West Lafayette, IN, USA
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29
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Behnia K, Aubin H. Nernst effect in metals and superconductors: a review of concepts and experiments. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:046502. [PMID: 27010481 DOI: 10.1088/0034-4885/79/4/046502] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The Nernst effect is the transverse electric field produced by a longitudinal thermal gradient in the presence of a magnetic field. At the beginning of this century, Nernst experiments on cuprates were analyzed assuming that: (i) the contribution of quasi-particles to the Nernst signal is negligible; and (ii) Gaussian superconducting fluctuations cannot produce a Nernst signal well above the critical temperature. Both these assumptions were contradicted by subsequent experiments. This paper reviews experiments documenting multiple sources of a Nernst signal, which, according to the Bridgman relation, measures the flow of transverse entropy caused by a longitudinal particle flow. Along the lines of Landauer's approach to transport phenomena, the magnitude of the transverse magneto-thermoelectric response is linked to the quantum of thermoelectric conductance and a number of material-dependent length scales: the mean free path, the Fermi wavelength, the de Broglie thermal wavelength and the superconducting coherence length. Extremely mobile quasi-particles in dilute metals generate a widely-documented Nernst signal. Fluctuating Cooper pairs in the normal state of superconductors have been found to produce a detectable Nernst signal with an amplitude conforming to the Gaussian theory, first conceived by Ussishkin, Sondhi and Huse. In addition to these microscopic sources, mobile Abrikosov vortices, mesoscopic objects simultaneously carrying entropy and magnetic flux, can produce a sizeable Nernst response. Finally, in metals subject to a magnetic field strong enough to truncate the Fermi surface to a few Landau tubes, each exiting tube generates a peak in the Nernst response. The survey of these well-established sources of the Nernst signal is a helpful guide to identify the origin of the Nernst signal in other controversial cases.
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Affiliation(s)
- Kamran Behnia
- Laboratoire de Physique et d'Etude des Matériaux, (Centre National de la Recherche Scientifique-Université Pierre et Marie Curie), Ecole Supérieure de Physique et de Chimie Industrielles, 75005 Paris, France
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30
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Giant phonon anomaly associated with superconducting fluctuations in the pseudogap phase of cuprates. Nat Commun 2016; 7:10378. [PMID: 26785835 PMCID: PMC4735821 DOI: 10.1038/ncomms10378] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 12/04/2015] [Indexed: 11/13/2022] Open
Abstract
The pseudogap in underdoped cuprates leads to significant changes in the electronic structure, and was later found to be accompanied by anomalous fluctuations of superconductivity and certain lattice phonons. Here we propose that the Fermi surface breakup due to the pseudogap, leads to a breakup of the pairing order into two weakly coupled sub-band amplitudes, and a concomitant low energy Leggett mode due to phase fluctuations between them. This increases the temperature range of superconducting fluctuations containing an overdamped Leggett mode. In this range inter-sub-band phonons show strong damping due to resonant scattering into an intermediate state with a pair of overdamped Leggett modes. In the ordered state, the Leggett mode develops a finite energy, changing the anomalous phonon damping into an anomaly in the dispersion. This proposal explains the intrinsic connection between the anomalous pseudogap phase, enhanced superconducting fluctuations and giant anomalies in the phonon spectra. The emergence of a giant phonon anomaly in the pseudogap phase of underdoped cuprate superconductors has been assumed to be a consequence of instability towards a charge density wave state. Here, the authors present a theory suggesting the anomaly arises due to large superconducting fluctuations.
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31
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Ishida Y, Saitoh T, Mochiku T, Nakane T, Hirata K, Shin S. Quasi-particles ultrafastly releasing kink bosons to form Fermi arcs in a cuprate superconductor. Sci Rep 2016; 6:18747. [PMID: 26728626 PMCID: PMC4700524 DOI: 10.1038/srep18747] [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: 08/20/2015] [Accepted: 11/25/2015] [Indexed: 01/12/2023] Open
Abstract
In a conventional framework, superconductivity is lost at a critical temperature (Tc) because, at higher temperatures, gluing bosons can no longer bind two electrons into a Cooper pair. In high-Tc cuprates, it is still unknown how superconductivity vanishes at Tc. We provide evidence that the so-called ≲70-meV kink bosons that dress the quasi-particle excitations are playing a key role in the loss of superconductivity in a cuprate. We irradiated a 170-fs laser pulse on Bi2Sr2CaCu2O8+δ and monitored the responses of the superconducting gap and dressed quasi-particles by time- and angle-resolved photoemission spectroscopy. We observe an ultrafast loss of superconducting gap near the d-wave node, or light-induced Fermi arcs, which is accompanied by spectral broadenings and weight redistributions occurring within the kink binding energy. We discuss that the underlying mechanism of the spectral broadening that induce the Fermi arc is the undressing of quasi-particles from the kink bosons. The loss mechanism is beyond the conventional framework, and can accept the unconventional phenomena such as the signatures of Cooper pairs remaining at temperatures above Tc.
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Affiliation(s)
- Y Ishida
- ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
| | - T Saitoh
- ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
| | - T Mochiku
- National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - T Nakane
- National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - K Hirata
- National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - S Shin
- ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.,CREST JST, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
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32
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Chatterjee U, Zhao J, Iavarone M, Di Capua R, Castellan JP, Karapetrov G, Malliakas CD, Kanatzidis MG, Claus H, Ruff JPC, Weber F, van Wezel J, Campuzano JC, Osborn R, Randeria M, Trivedi N, Norman MR, Rosenkranz S. Emergence of coherence in the charge-density wave state of 2H-NbSe2. Nat Commun 2015; 6:6313. [PMID: 25687135 PMCID: PMC4339883 DOI: 10.1038/ncomms7313] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 01/19/2015] [Indexed: 12/02/2022] Open
Abstract
A charge-density wave (CDW) state has a broken symmetry described by a complex order parameter with an amplitude and a phase. The conventional view, based on clean, weak-coupling systems, is that a finite amplitude and long-range phase coherence set in simultaneously at the CDW transition temperature Tcdw. Here we investigate, using photoemission, X-ray scattering and scanning tunnelling microscopy, the canonical CDW compound 2H-NbSe2 intercalated with Mn and Co, and show that the conventional view is untenable. We find that, either at high temperature or at large intercalation, CDW order becomes short-ranged with a well-defined amplitude, which has impacts on the electronic dispersion, giving rise to an energy gap. The phase transition at Tcdw marks the onset of long-range order with global phase coherence, leading to sharp electronic excitations. Our observations emphasize the importance of phase fluctuations in strongly coupled CDW systems and provide insights into the significance of phase incoherence in ‘pseudogap’ states. Charge density waves are described by a complex order parameter whose amplitude is expected to vanish at the transition temperature. This study shows that the transition in 2H-NbSe2 is driven by fluctuations of the phase of the order parameter, with a finite amplitude surviving in the disordered state.
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Affiliation(s)
- U Chatterjee
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Department of Physics, University of Virginia, Charlottesville, Virginia 22904, USA
| | - J Zhao
- 1] Department of Physics, University of Virginia, Charlottesville, Virginia 22904, USA [2] Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, USA
| | - M Iavarone
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - R Di Capua
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - J P Castellan
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Institute of Solid State Physics, Karlsruhe Institute of Technology, PO Box 3640, D-76021 Karlsruhe, Germany
| | - G Karapetrov
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, USA
| | - C D Malliakas
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - M G Kanatzidis
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - H Claus
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - J P C Ruff
- 1] Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] CHESS, Cornell University, Ithaca, New York 14853, USA
| | - F Weber
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Institute of Solid State Physics, Karlsruhe Institute of Technology, PO Box 3640, D-76021 Karlsruhe, Germany
| | - J van Wezel
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Institute for Theoretical Physics, University of Amsterdam, Tyndall Avenue, 1090 GL Amsterdam, The Netherlands
| | - J C Campuzano
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, USA
| | - R Osborn
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - M Randeria
- Department of Physics, Ohio State University, Columbus, Ohio 43210, USA
| | - N Trivedi
- Department of Physics, Ohio State University, Columbus, Ohio 43210, USA
| | - M R Norman
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - S Rosenkranz
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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33
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Resonant tunneling of fluctuation Cooper pairs. Sci Rep 2015; 5:8315. [PMID: 25661237 PMCID: PMC4321188 DOI: 10.1038/srep08315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 01/13/2015] [Indexed: 12/03/2022] Open
Abstract
Superconducting fluctuations have proved to be an irreplaceable source of information about microscopic and macroscopic material parameters that could be inferred from the experiment. According to common wisdom, the effect of thermodynamic fluctuations in the vicinity of the superconducting transition temperature, Tc, is to round off all of the sharp corners and discontinuities, which otherwise would have been expected to occur at Tc. Here we report the current spikes due to radiation-induced resonant tunneling of fluctuation Cooper pairs between two superconductors which grow even sharper and more pronounced upon approach to Tc. This striking effect offers an unprecedented tool for direct measurements of fluctuation Cooper pair lifetime, which is key to our understanding of the fluctuation regime, most notably to nature of the pseudogap state in high-temperature superconductors. Our finding marks a radical departure from the conventional view of superconducting fluctuations as a blurring and rounding phenomenon.
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34
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Chan MK, Veit MJ, Dorow CJ, Ge Y, Li Y, Tabis W, Tang Y, Zhao X, Barišić N, Greven M. In-plane magnetoresistance obeys Kohler's rule in the pseudogap phase of cuprate superconductors. PHYSICAL REVIEW LETTERS 2014; 113:177005. [PMID: 25379934 DOI: 10.1103/physrevlett.113.177005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Indexed: 06/04/2023]
Abstract
We report in-plane resistivity (ρ) and transverse magnetoresistance (MR) measurements for underdoped HgBa(2)CuO(4+δ) (Hg1201). Contrary to the long-standing view that Kohler's rule is strongly violated in underdoped cuprates, we find that it is in fact satisfied in the pseudogap phase of Hg1201. The transverse MR shows a quadratic field dependence, δρ/ρ(0)=aH(2), with a(T)∝T(-4). In combination with the observed ρ∝T(2) dependence, this is consistent with a single Fermi-liquid quasiparticle scattering rate. We show that this behavior is typically masked in cuprates with lower structural symmetry or strong disorder effects.
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Affiliation(s)
- M K Chan
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - M J Veit
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - C J Dorow
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Y Ge
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Y Li
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - W Tabis
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA and AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Al. A. Mickiewicza 30, 30-059 Krakow, Poland
| | - Y Tang
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - X Zhao
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA and State Key Lab of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, China
| | - N Barišić
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA and Service de Physique de l'Etat Condensé, CEA-DSM-IRAMIS, F 91198 Gif-sur-Yvette, France and Institute of Solid State Physics, Vienna University of Technology, 1040 Vienna, Austria
| | - M Greven
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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35
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Bossoni L, Romanó L, Canfield PC, Lascialfari A. Non-conventional superconducting fluctuations in Ba(Fe1-xRhx)2As2 iron-based superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:405703. [PMID: 25229750 DOI: 10.1088/0953-8984/26/40/405703] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We measured the static uniform spin susceptibility of Ba(Fe(1-x)Rh(x))(2)As(2) iron-based superconductors, over a broad range of doping (0.041 ⩽ x ⩽ 0.094) and magnetic fields. At small fields (H ⩽ 1 kOe) we observed, above the transition temperature Tc, the occurrence of precursor diamagnetism, which is not ascribable to the Ginzburg-Landau theory. On the contrary, our data agree with a phase fluctuation model, which has been used to interpret a similar phenomenology occurring in the high-Tc cuprate superconductors. Additionally, in the presence of strong fields, the unconventional fluctuating diamagnetism is suppressed, whereas Ginzburg-Landau fluctuations are found, in agreement with literature.
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Affiliation(s)
- L Bossoni
- Department of Physics, University of Pavia-CNISM, Via Bassi 6, I-27100 Pavia, Italy
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36
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Hu W, Kaiser S, Nicoletti D, Hunt CR, Gierz I, Hoffmann MC, Le Tacon M, Loew T, Keimer B, Cavalleri A. Optically enhanced coherent transport in YBa2Cu3O6.5 by ultrafast redistribution of interlayer coupling. NATURE MATERIALS 2014; 13:705-11. [PMID: 24813422 DOI: 10.1038/nmat3963] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 03/28/2014] [Indexed: 05/23/2023]
Abstract
Nonlinear optical excitation of infrared active lattice vibrations has been shown to melt magnetic or orbital orders and to transform insulators into metals. In cuprates, this technique has been used to remove charge stripes and promote superconductivity, acting in a way opposite to static magnetic fields. Here, we show that excitation of large-amplitude apical oxygen distortions in the cuprate superconductor YBa2Cu3O6.5 promotes highly unconventional electronic properties. Below the superconducting transition temperature (Tc = 50 K) inter-bilayer coherence is transiently enhanced at the expense of intra-bilayer coupling. Strikingly, even above Tc a qualitatively similar effect is observed up to room temperature, with transient inter-bilayer coherence emerging from the incoherent ground state and similar transfer of spectral weight from high to low frequency. These observations are compatible with previous reports of an inhomogeneous normal state that retains important properties of a superconductor, in which light may be melting competing orders or dynamically synchronizing the interlayer phase. The transient redistribution of coherence discussed here could lead to new strategies to enhance superconductivity in steady state.
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Affiliation(s)
- W Hu
- 1] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2]
| | - S Kaiser
- 1] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2]
| | - D Nicoletti
- 1] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2]
| | - C R Hunt
- 1] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2] Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA [3]
| | - I Gierz
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - M C Hoffmann
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - M Le Tacon
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - T Loew
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - B Keimer
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - A Cavalleri
- 1] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2] Department of Physics, Oxford University, Clarendon Laboratory, Oxford OX1 3PU, UK
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37
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Hayward LE, Hawthorn DG, Melko RG, Sachdev S. Angular fluctuations of a multicomponent order describe the pseudogap of YBa2Cu3O(6+x). Science 2014; 343:1336-9. [PMID: 24653030 DOI: 10.1126/science.1246310] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The hole-doped cuprate high-temperature superconductors enter the pseudogap regime as their superconducting critical temperature, Tc, falls with decreasing hole density. Recent x-ray scattering experiments in YBa2Cu3O(6+x) observe incommensurate charge-density wave fluctuations whose strength rises gradually over a wide temperature range above Tc, but then decreases as the temperature is lowered below Tc. We propose a theory in which the superconducting and charge-density wave orders exhibit angular fluctuations in a six-dimensional space. The theory provides a natural quantitative fit to the x-ray data and can be a basis for understanding other characteristics of the pseudogap.
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Affiliation(s)
- Lauren E Hayward
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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38
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Kobayashi K, Satsukawa H, Yamada J, Terashima T, Uji S. Observation of orbital resonance Hall effect in (TMTSF)2ClO4. PHYSICAL REVIEW LETTERS 2014; 112:116805. [PMID: 24702404 DOI: 10.1103/physrevlett.112.116805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Indexed: 06/03/2023]
Abstract
We report the observation of a Hall effect driven by orbital resonance in the quasi-1-dimensional (q1D) organic conductor (TMTSF)2ClO4. Although a conventional Hall effect is not expected in this class of materials due to their reduced dimensionality, we observed a prominent Hall response at certain orientations of the magnetic field B corresponding to lattice vectors of the constituent molecular chains, known as the magic angles (MAs). We show that this Hall effect can be understood as the response of conducting planes generated by an effective locking of the orbital motion of the charge carriers to the MA driven by an electron-trajectory resonance. This phenomenon supports a class of theories describing the rich behavior of MA phenomena in q1D materials based on altered dimensionality. Furthermore, we observed that the effective carrier density of the conducting planes is exponentially suppressed in large B, which indicates possible density wave formation.
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Affiliation(s)
| | - H Satsukawa
- National Institute for Material Science, Ibaraki 305-0003, Japan
| | - J Yamada
- University of Hyogo, Hyogo 678-1297, Japan
| | - T Terashima
- National Institute for Material Science, Ibaraki 305-0003, Japan
| | - S Uji
- National Institute for Material Science, Ibaraki 305-0003, Japan
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39
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Li T, Liao H. Raman spectrum in the pseudogap phase of the underdoped cuprates: effect of phase coherence and the signature of the KT-type superconducting transition. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:464201. [PMID: 22052795 DOI: 10.1088/0953-8984/23/46/464201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The temperature evolution of the Raman spectrum of the underdoped cuprates is studied in the thermal phase fluctuation scenario with an XY-type lattice model for the phase degree of freedom. It is found that the pair breaking Raman peak depends sensitively on the phase coherence of the pairing order parameter. As a result, the integrated Raman intensity in both the B(1g) and the B(2g) channels exhibits a dramatic drop across the Kosterlitz-Thouless (KT) transition temperature (T(KT)), when vortex-like phase fluctuation is proliferated. This result, which is consistent with experimental observations, provides further support for the thermal phase fluctuation scenario of the pseudogap phase and the KT-type nature of the superconducting transition in underdoped cuprates.
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Affiliation(s)
- Tao Li
- Department of Physics, Renmin University of China, Beijing 100872, People's Republic of China
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40
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Pseudogap in a thin film of a conventional superconductor. Nat Commun 2011; 1:140. [PMID: 21266990 DOI: 10.1038/ncomms1140] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Accepted: 11/17/2010] [Indexed: 11/08/2022] Open
Abstract
A superconducting state is characterized by the gap in the electronic density of states, which vanishes at the superconducting transition temperature T(c). It was discovered that in high-temperature superconductors, a noticeable depression in the density of states, the pseudogap, still remains even at temperatures above T(c). Here, we show that a pseudogap exists in a conventional superconductor, ultrathin titanium nitride films, over a wide range of temperatures above T(c). Our study reveals that this pseudogap state is induced by superconducting fluctuations and favoured by two-dimensionality and by the proximity to the transition to the insulating state. A general character of the observed phenomenon provides a powerful tool to discriminate between fluctuations as the origin of the pseudogap state and other contributions in the layered high-temperature superconductor compounds.
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41
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Phillips P. Mottness collapse and T-linear resistivity in cuprate superconductors. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:1574-1598. [PMID: 21422016 DOI: 10.1098/rsta.2011.0004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Central to the normal state of cuprate high-temperature superconductors is the collapse of the pseudo-gap, briefly reviewed here, at a critical point and the subsequent onset of the strange metal characterized by a resistivity that scales linearly with temperature. A possible clue to the resolution of this problem is the inter-relation between two facts: (i) a robust theory of T-linear resistivity resulting from quantum criticality requires an additional length scale outside the standard one-parameter scaling scenario and (ii) breaking the Landau correspondence between the Fermi gas and an interacting system with short-range repulsions requires non-fermionic degrees. We show that a low-energy theory of the Hubbard model that correctly incorporates dynamical spectral weight transfer has the extra degrees of freedom needed to describe this physics. The degrees of freedom that mix into the lower band as a result of dynamical spectral weight transfer are shown to either decouple beyond a critical doping, thereby signalling Mottness collapse, or unbind above a critical temperature, yielding strange metal behaviour characterized by T-linear resistivity.
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Affiliation(s)
- Philip Phillips
- Department of Physics, University of Illinois, 1110 West Green Street, Urbana, IL 61801, USA.
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42
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The Meissner effect in a strongly underdoped cuprate above its critical temperature. Nat Commun 2011; 2:272. [PMID: 21505428 PMCID: PMC3104550 DOI: 10.1038/ncomms1273] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 03/11/2011] [Indexed: 12/02/2022] Open
Abstract
The Meissner effect and associated perfect 'bulk' diamagnetism together with zero resistance and gap opening are characteristic features of the superconducting state. In the pseudogap state of cuprates, unusual diamagnetic signals and anomalous proximity effects have been detected, but a Meissner effect has never been observed. Here we probe the local diamagnetic response in the normal state of an underdoped La1.94Sr0.06CuO4 layer (Tc′≤5 K), which is brought into close contact with two nearly optimally doped La1.84Sr0.16CuO4 layers (Tc≈32 K). We show that the entire 'barrier' layer of thickness, much larger than the typical c axis coherence lengths of cuprates, exhibits a Meissner effect at temperatures above Tc′ but below Tc. The temperature dependence of the effective penetration depth and superfluid density in different layers indicates that superfluidity with long-range phase coherence is induced in the underdoped layer by the proximity to optimally doped layers, but this induced order is sensitive to thermal excitation. In the pseudogap state of cuprates, although diamagnetic signals have been detected, a Meissner effect has never been observed. Morenzoni and colleagues probe the local diamagnetic response in the normal state of an underdoped layer showing that a 'barrier' layer exhibits a Meissner effect.
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43
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Li T, Han Q. On the origin of the Fermi arc phenomenon in the underdoped cuprates: signature of KT-type superconducting transition. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:105603. [PMID: 21335633 DOI: 10.1088/0953-8984/23/10/105603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The origin of the Fermi arc phenomenon in the pseudogap phase of the underdoped cuprates is studied in the thermal phase fluctuation scenario. An XY-type lattice model with a built in d-wave structure is introduced to describe the phase fluctuation effect in the cuprates. A sharp ridge-like structure in the spectral function A(k, ω = 0) is found to emerge abruptly above the Kosterlitz-Thouless (KT) transition temperature (T(KT)) on the underlying Fermi surface. This ridge-like structure in A(k, ω = 0) bears a close resemblance to the observed Fermi arc phenomenon in its temperature dependence and shape in the momentum space. These results provide yet more strong evidence for the KT transition nature of the superconducting transition in the underdoped cuprates.
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Affiliation(s)
- Tao Li
- Department of Physics, Renmin University of China, Beijing 100872, People's Republic of China
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44
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Zhu Z, Yang H, Banerjee A, Malone L, Fauqué B, Behnia K. Nernst quantum oscillations in bulk semi-metals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:094204. [PMID: 21339557 DOI: 10.1088/0953-8984/23/9/094204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
With a widely available magnetic field of 10 T, one can attain the quantum limit in bismuth and graphite. At zero magnetic field, these two elemental semi-metals host a dilute liquid of carriers of both signs. All quasi-particles are confined to a few Landau tubes, when the quantum limit is attained. Each time a Landau tube is squeezed before definitely leaving the Fermi surface, the Nernst response sharply peaks. For bismuth, additional Nernst peaks, unexpected in the non-interacting picture, are resolved beyond the quantum limit. The amplitudes of these unexpected Nernst peaks become more pronounced for the samples with the longest electron mean free path.
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Affiliation(s)
- Zengwei Zhu
- LPEM (UPMC-CNRS), Ecole Supérieure de Physique et de Chimie Industrielles, Paris, France
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45
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Fausti D, Tobey RI, Dean N, Kaiser S, Dienst A, Hoffmann MC, Pyon S, Takayama T, Takagi H, Cavalleri A. Light-induced superconductivity in a stripe-ordered cuprate. Science 2011; 331:189-91. [PMID: 21233381 DOI: 10.1126/science.1197294] [Citation(s) in RCA: 279] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
One of the most intriguing features of some high-temperature cuprate superconductors is the interplay between one-dimensional "striped" spin order and charge order, and superconductivity. We used mid-infrared femtosecond pulses to transform one such stripe-ordered compound, nonsuperconducting La(1.675)Eu(0.2)Sr(0.125)CuO(4), into a transient three-dimensional superconductor. The emergence of coherent interlayer transport was evidenced by the prompt appearance of a Josephson plasma resonance in the c-axis optical properties. An upper limit for the time scale needed to form the superconducting phase is estimated to be 1 to 2 picoseconds, which is significantly faster than expected. This places stringent new constraints on our understanding of stripe order and its relation to superconductivity.
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Affiliation(s)
- D Fausti
- Max Planck Research Department for Structural Dynamics, University of Hamburg-Centre for Free Electron Laser Science-Hamburg, Germany.
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46
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Sonier JE. High-field μSR studies of superconducting and magnetic correlations in cuprates above T(c). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:203202. [PMID: 21393701 DOI: 10.1088/0953-8984/22/20/203202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The advent of high transverse field muon spin rotation (TF-μSR) has led to recent μSR investigations of the magnetic field response of cuprates above the superconducting transition temperature T(c). Here the results of such experiments on hole-doped cuprates are reviewed. Although these investigations are currently ongoing, it is clear that the effects of high field on the internal magnetic field distribution of these materials is dependent upon competition between superconductivity and magnetism. In La(2 - x)Sr(x)CuO(4) the response to the external field above T(c) is dominated by heterogeneous spin magnetism. However, the magnetism that dominates the observed inhomogeneous line broadening below x ∼ 0.19 is overwhelmed by the emergence of a completely different kind of magnetism in the heavily overdoped regime. The origin of the magnetism above x ∼ 0.19 is probably related to intrinsic disorder, but the systematic evolution of the magnetism with doping changes in the doping range beyond the superconducting 'dome'. In contrast, the width of the internal field distribution of underdoped Y Ba(2)Cu(3)O(y) above T(c) is observed to track T(c) and the density of superconducting carriers. This observation suggests that the magnetic response above T(c) is not dominated by electronic moments, but rather inhomogeneous fluctuating superconductivity. The spatially inhomogeneous response of Y Ba(2)Cu(3)O(y) to the applied field may be a means of minimizing energy, rather than being caused by intrinsic disorder.
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Affiliation(s)
- J E Sonier
- Department of Physics, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.
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47
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Tao Q, Zhu Z, Lin X, Cao G, Xu ZA, Chen G, Luo J, Wang N. A comparative study on the thermoelectric effect of parent oxypnictides LaTAsO (T = Fe, Ni). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:072201. [PMID: 21386374 DOI: 10.1088/0953-8984/22/7/072201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The thermopower and Nernst effect were investigated for undoped parent compounds LaFeAsO and LaNiAsO. Both the thermopower and Nernst signal in iron-based LaFeAsO are significantly larger than those in nickel-based LaNiAsO. Furthermore, abrupt changes in both the thermopower and Nernst effect are observed below the structural phase transition temperature and spin-density wave (SDW) type antiferromagnetic (AFM) order temperature in Fe-based LaFeAsO. On the other hand, the Nernst effect is very small in the Ni-based LaNiAsO and it is weakly temperature-dependent, reminiscent of the case in normal metals. We suggest that the effect of SDW order on the spin scattering rate should play an important role in the anomalous temperature dependence of the Hall effect and Nernst effect in LaFeAsO. The contrasting behaviour between the LaFeAsO and LaNiAsO systems implies that the LaFeAsO system is fundamentally different from the LaNiAsO system and this may provide clues to the mechanism of high T(c) superconductivity in Fe-based systems.
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Affiliation(s)
- Qian Tao
- Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
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48
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Bergman DL, Oganesyan V. Theory of dissipationless Nernst effects. PHYSICAL REVIEW LETTERS 2010; 104:066601. [PMID: 20366843 DOI: 10.1103/physrevlett.104.066601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Indexed: 05/29/2023]
Abstract
We develop a theory of transverse thermoelectric (Peltier) conductivity alpha(xy), in a strong magnetic field--this particular conductivity is often the most important contribution to the Nernst thermopower. We demonstrate that alpha(xy) of a free electron gas can be expressed purely and exactly as the entropy per carrier irrespective of temperature (which agrees with the seminal Hall bar result of Girvin and Jonson). In two dimensions we prove the universality of this result in the presence of disorder which allows explicit demonstration of a number of features of interest to experiments on graphene and other two-dimensional materials. We also exploit this relationship in the low-field regime and analyze the rich singularity structure in alpha(xy)(B,T) in three dimensions; we discuss its possible experimental implications.
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Affiliation(s)
- Doron L Bergman
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
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49
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Kuepper K, Wintz S, Raabe J, Buess M, Akhmadaliev C, Bischoff L, Quitmann C, Fassbender J. Magnetization dynamics of Landau structures: tuning the response of mesoscopic magnetic objects using defects. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:436003. [PMID: 21832449 DOI: 10.1088/0953-8984/21/43/436003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Magnetic vortex cores are interacting with and can even be annihilated by artificial defects, such as holes. These defects have been fabricated by focused ion beam milling (FIB) into the magnetic domains, domain walls and the center of square-shaped vortices, known as Landau structures. We report the imaging of the magnetization dynamics of Landau structures containing holes by means of x-ray magnetic circular dichroism photo-emission electron microscopy (XMCD-PEEM). Due to the high lateral and temporal resolution of this method, the magnetic excitation spectrum, which is characteristic for the vortex-hole interaction, is investigated in detail. We find that the vortex core as well as domain walls can be trapped by small holes. With the help of micromagnetic simulations we show that the vortex gyrotropic motion frequency is enhanced, whereas the amplitude is significantly reduced in the case of non-centric holes in domain walls.
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Affiliation(s)
- K Kuepper
- Institut für Festkörperphysik, University of Ulm, Albert-Einstein-Allee 11, D-89069 Ulm, GermanyPresent address
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Andersson DA, Casillas L, Baskes MI, Lezama JS, Conradson SD. Modeling of the phase evolution in Mg1-xAlxB2 (0 < x < 0.5) and its experimental signatures. J Phys Chem B 2009; 113:11965-76. [PMID: 19673495 DOI: 10.1021/jp902505r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Despite the chemical and structural simplicity of MgB(2), at 39 K this compound has the highest known superconducting transition temperature (T(c)) of any binary compound. Electron doping by substituting Al for Mg leads to decreasing T(c), and the observed concentration dependent rate of decrease has been proposed to arise from the nonideal character of MgB(2)-AlB(2) solid solutions, which derives from the existence of an ordered Mg(0.5)Al(0.5)B(2) compound. Heterogeneous nanoscale structure patterns in solid solutions have emerged as an important concept for complex materials, ranging from actinide alloys and oxides to high-temperature cuprate superconductors and manganite-based materials exhibiting colossal magnetoresistivity. In this work we investigate the formation of structural heterogeneities in Mg(1-x)Al(x)B(2), which take the form of nanoscale Al-Al and Al-Mg domains of different geometries and sizes, using molecular statics and Monte Carlo simulations, and in particular we study the corresponding signatures in diffraction experiments. In order to undertake this task, we first derive appropriate Mg-Al-B semiempirical potentials within the modified embedded atom method formalism. These potentials are also applied to explore the equilibrium Mg(1-x)Al(x)B(2) phase diagram for 0 < x < 0.5. Additionally, density functional theory calculations were utilized to study the influence of heterogeneities on the electronic structure and charge distribution in Mg(1-x)Al(x)B(2).
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Affiliation(s)
- David A Andersson
- Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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