1
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Zhao Y, Ying T, Zhao L, Wu J, Pei C, Chen J, Deng J, Zhang Q, Gu L, Wang Q, Cao W, Li C, Zhu S, Zhang M, Yu N, Zhang L, Chen Y, Chen CZ, Yu T, Qi Y. Disorder-Broadened Phase Boundary with Enhanced Amorphous Superconductivity in Pressurized In 2Te 5. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2401118. [PMID: 38641859 DOI: 10.1002/adma.202401118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/20/2024] [Indexed: 04/21/2024]
Abstract
As an empirical tool in materials science and engineering, the iconic phase diagram owes its robustness and practicality to the topological characteristics rooted in the celebrated Gibbs phase law free variables (F) = components (C) - phases (P) + 2. When crossing the phase diagram boundary, the structure transition occurs abruptly, bringing about an instantaneous change in physical properties and limited controllability on the boundaries (F = 1). Here, the sharp phase boundary is expanded to an amorphous transition region (F = 2) by partially disrupting the long-range translational symmetry, leading to a sequential crystalline-amorphous-crystalline (CAC) transition in a pressurized In2Te5 single crystal. Through detailed in situ synchrotron diffraction, it is elucidated that the phase transition stems from the rotation of immobile blocks [In2Te2]2+, linked by hinge-like [Te3]2- trimers. Remarkably, within the amorphous region, the amorphous phase demonstrates a notable 25% increase of the superconducting transition temperature (Tc), while the carrier concentration remains relatively constant. Furthermore, a theoretical framework is proposed revealing that the unconventional boost in amorphous superconductivity might be attributed to an intensified electron correlation, triggered by a disorder-augmented multifractal behavior. These findings underscore the potential of disorder and prompt further exploration of unforeseen phenomena on the phase boundaries.
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Affiliation(s)
- Yi Zhao
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Tianping Ying
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100190, China
| | - Lingxiao Zhao
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Juefei Wu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Cuiying Pei
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Jing Chen
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100190, China
| | - Jun Deng
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100190, China
| | - Qinghua Zhang
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100190, China
| | - Lin Gu
- Beijing National Center for Electron Microscopy and Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China
| | - Qi Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai, 201210, China
| | - Weizheng Cao
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Changhua Li
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Shihao Zhu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Mingxin Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Na Yu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Lili Zhang
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Yulin Chen
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai, 201210, China
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU, UK
| | - Chui-Zhen Chen
- Institute for Advanced Study and School of Physical Science and Technology, Soochow University, Suzhou, 215006, China
| | - Tongxu Yu
- Suzhou Laboratory, Suzhou, Jiangsu, 215123, China
| | - Yanpeng Qi
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai, 201210, China
- Shanghai Key Laboratory of High-resolution Electron Microscopy, ShanghaiTech University, Shanghai, 201210, China
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2
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Vaňo V, Ganguli SC, Amini M, Yan L, Khosravian M, Chen G, Kezilebieke S, Lado JL, Liljeroth P. Evidence of Nodal Superconductivity in Monolayer 1H-TaS 2 with Hidden Order Fluctuations. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2305409. [PMID: 37592888 DOI: 10.1002/adma.202305409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 08/07/2023] [Indexed: 08/19/2023]
Abstract
Unconventional superconductors represent one of the fundamental directions in modern quantum materials research. In particular, nodal superconductors are known to appear naturally in strongly correlated systems, including cuprate superconductors and heavy-fermion systems. Van der Waals materials hosting superconducting states are well known, yet nodal monolayer van der Waals superconductors have remained elusive. Here, using low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS) experiments, it is shown that pristine monolayer 1H-TaS2 realizes a nodal superconducting state. Non-magnetic disorder drives the nodal superconducting state to a conventional gapped s-wave state. Furthermore, many-body excitations emerge close to the gap edge, signalling a potential unconventional pairing mechanism. The results demonstrate the emergence of nodal superconductivity in a van der Waals monolayer, providing a building block for van der Waals heterostructures exploiting unconventional superconducting states.
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Affiliation(s)
- Viliam Vaňo
- Department of Applied Physics, Aalto University, FI-00076, Aalto, Finland
| | | | - Mohammad Amini
- Department of Applied Physics, Aalto University, FI-00076, Aalto, Finland
| | - Linghao Yan
- Department of Applied Physics, Aalto University, FI-00076, Aalto, Finland
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu, 215123, P. R. China
| | - Maryam Khosravian
- Department of Applied Physics, Aalto University, FI-00076, Aalto, Finland
| | - Guangze Chen
- Department of Applied Physics, Aalto University, FI-00076, Aalto, Finland
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg, 41296, Sweden
| | - Shawulienu Kezilebieke
- Department of Physics, Department of Chemistry and Nanoscience Center, University of Jyväskylä, University of Jyväskylä, FI-40014, Finland
| | - Jose L Lado
- Department of Applied Physics, Aalto University, FI-00076, Aalto, Finland
| | - Peter Liljeroth
- Department of Applied Physics, Aalto University, FI-00076, Aalto, Finland
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3
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Caldas H, Rufo S, Griffith MAR. Non-homogeneous pairing in disordered two-orbital s-wave superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 36:055601. [PMID: 37820641 DOI: 10.1088/1361-648x/ad0275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 10/11/2023] [Indexed: 10/13/2023]
Abstract
We investigate the effects of non-magnetic disorder in a hybridized two-dimensional two-orbital s-wave superconductor (SC) model. The situation in which electronic orbitals overlap such that the hybridizationVi,jamong them is antisymmetric, under inversion symmetry, was taken into account. The on-site disorder is given by a random impurity potentialW. We find that while the random disorder acts to the detriment of superconductivity, hybridization proceeds to favor it. Accordingly, hybridization plays an important role in two-orbital models of superconductivity, in order to hold the long-range order against the increase of disorder. This makes the present model eligible to describe real materials, since the hybridization may be induced by pressure or doping. In addition, the regime from moderate to strong disorder reveals that the system is broken into SC islands with correlated local order parameters. These correlations persist to distances of several order lattice spacing which corresponds to the size of the SC-Islands.
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Affiliation(s)
- Heron Caldas
- Departamento de Ciências Naturais, Universidade Federal de São João Del Rei, Praça Dom Helvécio 74, 36301-160 São João Del Rei, MG, Brazil
| | - S Rufo
- Beijing Computational Science Research Center, Building 9, East Zone, No. 10 East Xibeiwang Road, Haidian District, Beijing 100193, People's Republic of China
- CeFEMA, Instituto Superior técnico, Universidade de Lisboa, Av. Rovisco Pais, No. 1, 1049-001 Lisboa, Portugal
| | - M A R Griffith
- Beijing Computational Science Research Center, Building 9, East Zone, No. 10 East Xibeiwang Road, Haidian District, Beijing 100193, People's Republic of China
- CeFEMA, Instituto Superior técnico, Universidade de Lisboa, Av. Rovisco Pais, No. 1, 1049-001 Lisboa, Portugal
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4
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Manasa M, Azam M, Zajarniuk T, Diduszko R, Cetner T, Morawski A, Wiśniewski A, Singh SJ. Cometal Addition Effect on Superconducting Properties and Granular Behaviours of Polycrystalline FeSe 0.5Te 0.5. MATERIALS (BASEL, SWITZERLAND) 2023; 16:2892. [PMID: 37049186 PMCID: PMC10095744 DOI: 10.3390/ma16072892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/01/2023] [Accepted: 04/03/2023] [Indexed: 06/19/2023]
Abstract
The enhanced performance of superconducting FeSe0.5Te0.5 materials with added micro-sized Pb and Sn particles is presented. A series of Pb- and Sn-added FeSe0.5Te0.5 (FeSe0.5Te0.5 + xPb + ySn; x = y = 0-0.1) bulks are fabricated by the solid-state reaction method and characterized through various measurements. A very small amount of Sn and Pb additions (x = y ≤ 0.02) enhance the transition temperature (Tconset) of pure FeSe0.5Te0.5 by ~1 K, sharpening the superconducting transition and improving the metallic nature in the normal state, whereas larger metal additions (x = y ≥ 0.03) reduce Tconset by broadening the superconducting transition. Microstructural analysis and transport studies suggest that at x = y > 0.02, Pb and Sn additions enhance the impurity phases, reduce the coupling between grains, and suppress the superconducting percolation, leading to a broad transition. FeSe0.5Te0.5 samples with 2 wt% of cometal additions show the best performance with their critical current density, Jc, and the pinning force, Fp, which might be attributable to providing effective flux pinning centres. Our study shows that the inclusion of a relatively small amount of Pb and Sn (x = y ≤ 0.02) works effectively for the enhancement of superconducting properties with an improvement of intergrain connections as well as better phase uniformity.
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Affiliation(s)
- Manasa Manasa
- Institute of High Pressure Physics (IHPP), Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw, Poland
| | - Mohammad Azam
- Institute of High Pressure Physics (IHPP), Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw, Poland
| | - Tatiana Zajarniuk
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland
| | - Ryszard Diduszko
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland
- Institute of Microelectronics and Photonics, Wólczyńska 133, 01-919 Warsaw, Poland
| | - Tomasz Cetner
- Institute of High Pressure Physics (IHPP), Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw, Poland
| | - Andrzej Morawski
- Institute of High Pressure Physics (IHPP), Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw, Poland
| | - Andrzej Wiśniewski
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland
| | - Shiv J. Singh
- Institute of High Pressure Physics (IHPP), Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw, Poland
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5
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Fan B, Samanta A, García-García AM. Tuning Superinductors by Quantum Coherence Effects for Enhancing Quantum Computing. PHYSICAL REVIEW LETTERS 2023; 130:047001. [PMID: 36763448 DOI: 10.1103/physrevlett.130.047001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 09/22/2022] [Accepted: 01/06/2023] [Indexed: 06/18/2023]
Abstract
Research on spatially inhomogeneous weakly coupled superconductors has recently received a boost of interest because of the experimental observation of a dramatic enhancement of the kinetic inductance with relatively low losses. Here, we study the kinetic inductance and the quality factor of a strongly disordered, weakly coupled superconducting thin film. We employ a gauge-invariant random-phase approximation capable of describing collective excitations and other fluctuations. In line with the experimental findings, we have found that in the range of frequencies of interest, and for sufficiently low temperatures, an exponential increase of the kinetic inductance with disorder coexists with a still large quality factor of ∼10^{4}. More interestingly, on the metallic side of the superconductor-insulator transition, we have identified a range of frequencies and temperatures, T∼0.1T_{c}, where quantum coherence effects induce a broad statistical distribution of the quality factor with an average value that increases with disorder. We expect these findings to further stimulate experimental research on the design and optimization of superinductors for a better performance and miniaturization of quantum devices such as qubit circuits and microwave detectors.
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Affiliation(s)
- Bo Fan
- Shanghai Center for Complex Physics, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | | | - Antonio M García-García
- Shanghai Center for Complex Physics, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
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6
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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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7
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An FA, Padavić K, Meier EJ, Hegde S, Ganeshan S, Pixley JH, Vishveshwara S, Gadway B. Interactions and Mobility Edges: Observing the Generalized Aubry-André Model. PHYSICAL REVIEW LETTERS 2021; 126:040603. [PMID: 33576679 DOI: 10.1103/physrevlett.126.040603] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 12/04/2020] [Accepted: 01/08/2021] [Indexed: 06/12/2023]
Abstract
Using synthetic lattices of laser-coupled atomic momentum modes, we experimentally realize a recently proposed family of nearest-neighbor tight-binding models having quasiperiodic site energy modulation that host an exact mobility edge protected by a duality symmetry. These one-dimensional tight-binding models can be viewed as a generalization of the well-known Aubry-André model, with an energy-dependent self-duality condition that constitutes an analytical mobility edge relation. By adiabatically preparing low and high energy eigenstates of this model system and performing microscopic measurements of their participation ratio, we track the evolution of the mobility edge as the energy-dependent density of states is modified by the model's tuning parameter. Our results show strong deviations from single-particle predictions, consistent with attractive interactions causing both enhanced localization of the lowest energy state due to self-trapping and inhibited localization of high energy states due to screening. This study paves the way for quantitative studies of interaction effects on self-duality induced mobility edges.
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Affiliation(s)
- Fangzhao Alex An
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
| | - Karmela Padavić
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
| | - Eric J Meier
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
| | - Suraj Hegde
- Max-Planck Institute for Physics of Complex Systems, 01187 Dresden, Germany
| | - Sriram Ganeshan
- Physics Department, City College of the CUNY, New York, New York 10031, USA
- CUNY Graduate Center, New York, New York 10031, USA
| | - J H Pixley
- Department of Physics and Astronomy, Center for Materials Theory, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Smitha Vishveshwara
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
| | - Bryce Gadway
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
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8
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Gao J, Park JW, Kim K, Song SK, Park HR, Lee J, Park J, Chen F, Luo X, Sun Y, Yeom HW. Pseudogap and Weak Multifractality in 2D Disordered Mott Charge-Density-Wave Insulator. NANO LETTERS 2020; 20:6299-6305. [PMID: 32787162 DOI: 10.1021/acs.nanolett.0c01607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We investigate electronic states of Se-substituted 1T-TaS2 by scanning tunneling microscopy/spectroscopy (STM/STS), where superconductivity emerges from the unique Mott-charge-density-wave (Mott-CDW) state. Spatially resolved STS measurements reveal that a pseudogap replaces the Mott gap with the CDW gaps intact. The pseudogap has little correlation with the unit-cell-to-unit-cell variation in the local Se concentration but appears globally. The correlation length of the local density of states (LDOS) is substantially enhanced at the Fermi energy and decays rapidly at high energies. Furthermore, the statistical analysis of LDOS indicates the weak multifractal behavior of the wave functions. These findings suggest a correlated metallic state induced by disorder and provide a new insight into the emerging superconductivity in two-dimensional materials.
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Affiliation(s)
- Jianhua Gao
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
| | - Jae Whan Park
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
| | - Kiseok Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Sun Kyu Song
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Hae Ryong Park
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Jhinhwan Lee
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
| | - Jewook Park
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
| | - Fangchu Chen
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
- University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Xuan Luo
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Yuping Sun
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
- Collaborative Innovation Centre of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - Han Woong Yeom
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
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9
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An C, Zhou Y, Chen C, Fei F, Song F, Park C, Zhou J, Rubahn HG, Moshchalkov VV, Chen X, Zhang G, Yang Z. Long-Range Ordered Amorphous Atomic Chains as Building Blocks of a Superconducting Quasi-One-Dimensional Crystal. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2002352. [PMID: 32705735 DOI: 10.1002/adma.202002352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 06/01/2020] [Indexed: 06/11/2023]
Abstract
Crystalline and amorphous structures are two of the most common solid-state phases. Crystals having orientational and periodic translation symmetries are usually both short-range and long-range ordered, while amorphous materials have no long-range order. Short-range ordered but long-range disordered materials are generally categorized into amorphous phases. In contrast to the extensively studied crystalline and amorphous phases, the combination of short-range disordered and long-range ordered structures at the atomic level is extremely rare and so far has only been reported for solvated fullerenes under compression. Here, a report on the creation and investigation of a superconducting quasi-1D material with long-range ordered amorphous building blocks is presented. Using a diamond anvil cell, monocrystalline (TaSe4 )2 I is compressed and a system is created where the TaSe4 atomic chains are in amorphous state without breaking the orientational and periodic translation symmetries of the chain lattice. Strikingly, along with the amorphization of the atomic chains, the insulating (TaSe4 )2 I becomes a superconductor. The data provide critical insight into a new phase of solid-state materials. The findings demonstrate a first ever case where superconductivity is hosted by a lattice with periodic but amorphous constituent atomic chains.
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Affiliation(s)
- Chao An
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
| | - Yonghui Zhou
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China
| | - Chunhua Chen
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China
| | - Fucong Fei
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Fengqi Song
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Changyong Park
- HPCAT, X-Ray Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Jianhui Zhou
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China
| | - Horst-Günter Rubahn
- NanoSYD, Mads Clausen Institute and DIAS Danish Institute for Advanced Study, University of Southern Denmark, Alsion 2, Sonderborg, DK-6400, Denmark
| | | | - Xuliang Chen
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China
| | - Gufei Zhang
- NanoSYD, Mads Clausen Institute and DIAS Danish Institute for Advanced Study, University of Southern Denmark, Alsion 2, Sonderborg, DK-6400, Denmark
| | - Zhaorong Yang
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China
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10
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Rubio-Verdú C, Garcı A-Garcı A AM, Ryu H, Choi DJ, Zaldı Var J, Tang S, Fan B, Shen ZX, Mo SK, Pascual JI, Ugeda MM. Visualization of Multifractal Superconductivity in a Two-Dimensional Transition Metal Dichalcogenide in the Weak-Disorder Regime. NANO LETTERS 2020; 20:5111-5118. [PMID: 32463696 DOI: 10.1021/acs.nanolett.0c01288] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Eigenstate multifractality is a distinctive feature of noninteracting disordered metals close to a metal-insulator transition, whose properties are expected to extend to superconductivity. While multifractality in three dimensions (3D) only develops near the critical point for specific strong-disorder strengths, multifractality in 2D systems is expected to be observable even for weak disorder. Here we provide evidence for multifractal features in the superconducting state of an intrinsic, weakly disordered single-layer NbSe2 by means of low-temperature scanning tunneling microscopy/spectroscopy. The superconducting gap, characterized by its width, depth, and coherence peaks' amplitude, shows a characteristic spatial modulation coincident with the periodicity of the quasiparticle interference pattern. The strong spatial inhomogeneity of the superconducting gap width, proportional to the local order parameter in the weak-disorder regime, follows a log-normal statistical distribution as well as a power-law decay of the two-point correlation function, in agreement with our theoretical model. Furthermore, the experimental singularity spectrum f(α) shows anomalous scaling behavior typical from 2D weakly disordered systems.
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Affiliation(s)
| | - Antonio M Garcı A-Garcı A
- Shanghai Center for Complex Physics, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hyejin Ryu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Center for Spintronics, Korean Institute of Science and Technology, Seoul 02792, Korea
| | - Deung-Jang Choi
- CIC nanoGUNE, 20018 Donostia-San Sebastián, Spain
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), 20018 San Sebastián, Spain
- Donostia International Physics Center (DIPC), 20018 San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
| | | | - Shujie Tang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Bo Fan
- Shanghai Center for Complex Physics, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zhi-Xun Shen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, California 94305, United States
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - José Ignacio Pascual
- CIC nanoGUNE, 20018 Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
| | - Miguel M Ugeda
- CIC nanoGUNE, 20018 Donostia-San Sebastián, Spain
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), 20018 San Sebastián, Spain
- Donostia International Physics Center (DIPC), 20018 San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
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11
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Rømer AT, Hirschfeld PJ, Andersen BM. Raising the Critical Temperature by Disorder in Unconventional Superconductors Mediated by Spin Fluctuations. PHYSICAL REVIEW LETTERS 2018; 121:027002. [PMID: 30085763 DOI: 10.1103/physrevlett.121.027002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Indexed: 06/08/2023]
Abstract
We propose a mechanism whereby disorder can enhance the transition temperature T_{c} of an unconventional superconductor with pairing driven by exchange of spin fluctuations. The theory is based on a self-consistent real space treatment of pairing in the disordered one-band Hubbard model. It has been demonstrated before that impurities can enhance pairing by softening the spin fluctuations locally; here, we consider the competing effect of pair breaking by the screened Coulomb potential also present. We show that, depending on the impurity potential strength and proximity to magnetic order, this mechanism results in a weakening of the disorder-dependent T_{c}-suppression rate expected from Abrikosov-Gor'kov theory, or even in disorder-generated T_{c} enhancements.
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Affiliation(s)
- Astrid T Rømer
- Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark
| | - P J Hirschfeld
- Department of Physics, University of Florida, Gainesville, Florida 32611, USA
| | - Brian M Andersen
- Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark
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12
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Feigel'man MV, Ioffe LB. Microwave Properties of Superconductors Close to the Superconductor-Insulator Transition. PHYSICAL REVIEW LETTERS 2018; 120:037004. [PMID: 29400488 DOI: 10.1103/physrevlett.120.037004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Indexed: 06/07/2023]
Abstract
Strongly disordered pseudogapped superconductors are expected to display arbitrarily high values of kinetic inductance close to the superconductor-insulator transition (SIT), which make them attractive for the implementation of large dissipationless inductance. We develop the theory of the collective modes in these superconductors and discuss associated dissipation at microwave frequencies. We obtain the collective mode spectra dependence on the disorder level and conclude that collective modes become a relevant source of dissipation and noise in the outer proximity of the SIT.
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Affiliation(s)
- M V Feigel'man
- L. D. Landau Institute for Theoretical Physics, Chernogolovka, Moscow region, 142432, Russia
- Skolkovo Institute of Science and Technology, Moscow, 143026, Russia
| | - L B Ioffe
- L. D. Landau Institute for Theoretical Physics, Chernogolovka, Moscow region, 142432, Russia
- National Research University "Higher School of Economics", Moscow, 101000, Russia
- LPTHE, Universite Pierre et Marie Curie, Paris, F-75005, France
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13
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Zhang G, Samuely T, Du H, Xu Z, Liu L, Onufriienko O, May PW, Vanacken J, Szabó P, Kačmarčík J, Yuan H, Samuely P, Dunin-Borkowski RE, Hofkens J, Moshchalkov VV. Bosonic Confinement and Coherence in Disordered Nanodiamond Arrays. ACS NANO 2017; 11:11746-11754. [PMID: 29125286 DOI: 10.1021/acsnano.7b07148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In the presence of disorder, superconductivity exhibits short-range characteristics linked to localized Cooper pairs which are responsible for anomalous phase transitions and the emergence of quantum states such as the bosonic insulating state. Complementary to well-studied homogeneously disordered superconductors, superconductor-normal hybrid arrays provide tunable realizations of the degree of granular disorder for studying anomalous quantum phase transitions. Here, we investigate the superconductor-bosonic dirty metal transition in disordered nanodiamond arrays as a function of the dispersion of intergrain spacing, which ranges from angstroms to micrometers. By monitoring the evolved superconducting gaps and diminished coherence peaks in the single-quasiparticle density of states, we link the destruction of the superconducting state and the emergence of bosonic dirty metallic state to breaking of the global phase coherence and persistence of the localized Cooper pairs. The observed resistive bosonic phase transitions are well modeled using a series-parallel circuit in the framework of bosonic confinement and coherence.
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Affiliation(s)
- Gufei Zhang
- INPAC-Insititute for Nanoscale Physics and Chemistry, KU Leuven , Celestijnenlaan 200D, B-3001 Heverlee, Belgium
| | - Tomas Samuely
- Centre of Low Temperature Physics, Institute of Experimental Physics, Slovak Academy of Sciences, and Faculty of Science, P. J. Safarik University , 04001 Kosice, Slovakia
| | - Hongchu Du
- Ernst Ruska Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH , Jülich 52425, Germany
- Central Facility for Electron Microscopy, RWTH Aachen University , Aachen 52074, Germany
| | - Zheng Xu
- School of Electrical and Computer Engineering, University of California , Davis, California 95616, United States
| | - Liwang Liu
- University of Bordeaux, CNRS, UMR 5295, I2M , F-33400 Talence, France
| | - Oleksandr Onufriienko
- Centre of Low Temperature Physics, Institute of Experimental Physics, Slovak Academy of Sciences, and Faculty of Science, P. J. Safarik University , 04001 Kosice, Slovakia
| | - Paul W May
- School of Chemistry, University of Bristol , Bristol BS8 1TS, United Kingdom
| | - Johan Vanacken
- INPAC-Insititute for Nanoscale Physics and Chemistry, KU Leuven , Celestijnenlaan 200D, B-3001 Heverlee, Belgium
| | - Pavol Szabó
- Centre of Low Temperature Physics, Institute of Experimental Physics, Slovak Academy of Sciences, and Faculty of Science, P. J. Safarik University , 04001 Kosice, Slovakia
| | - Jozef Kačmarčík
- Centre of Low Temperature Physics, Institute of Experimental Physics, Slovak Academy of Sciences, and Faculty of Science, P. J. Safarik University , 04001 Kosice, Slovakia
| | - Haifeng Yuan
- Department of Chemistry, KU Leuven , Celestijnenlaan 200F, B-3001 Heverlee, Belgium
| | - Peter Samuely
- Centre of Low Temperature Physics, Institute of Experimental Physics, Slovak Academy of Sciences, and Faculty of Science, P. J. Safarik University , 04001 Kosice, Slovakia
| | - Rafal E Dunin-Borkowski
- Ernst Ruska Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH , Jülich 52425, Germany
- Peter Grünberg Institute, Forschungszentrum Jülich GmbH , 52425 Jülich, Germany
| | - Johan Hofkens
- Department of Chemistry, KU Leuven , Celestijnenlaan 200F, B-3001 Heverlee, Belgium
| | - Victor V Moshchalkov
- INPAC-Insititute for Nanoscale Physics and Chemistry, KU Leuven , Celestijnenlaan 200D, B-3001 Heverlee, Belgium
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14
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Loh YL, Karki P. Dielectric and diamagnetic susceptibilities near percolative superconductor-insulator transitions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:425901. [PMID: 28829339 DOI: 10.1088/1361-648x/aa879d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Coarse-grained superconductor-insulator composites exhibit a superconductor-insulator transition governed by classical percolation, which should be describable by networks of inductors and capacitors. We study several classes of random inductor-capacitor networks on square lattices. We present a unifying framework for defining electric and magnetic response functions, and we extend the Frank-Lobb bond-propagation algorithm to compute these quantities by network reduction. We confirm that the superfluid stiffness scales approximately as [Formula: see text] as the superconducting bond fraction p approaches the percolation threshold p c . We find that the diamagnetic susceptibility scales as [Formula: see text] below percolation, and as [Formula: see text] above percolation. For models lacking self-capacitances, the electric susceptibility scales as [Formula: see text]. Including a self-capacitance on each node changes the critical behavior to approximately [Formula: see text].
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Affiliation(s)
- Yen Lee Loh
- Department of Physics and Astrophysics, University of North Dakota, Grand Forks, ND 58202, United States of America
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15
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Kettemann S. Exponential Orthogonality Catastrophe at the Anderson Metal-Insulator Transition. PHYSICAL REVIEW LETTERS 2016; 117:146602. [PMID: 27740783 DOI: 10.1103/physrevlett.117.146602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Indexed: 06/06/2023]
Abstract
We consider the orthogonality catastrophe at the Anderson metal-insulator transition (AMIT). The typical overlap F between the ground state of a Fermi liquid and the one of the same system with an added potential impurity is found to decay at the AMIT exponentially with system size L as F∼exp(-cL^{η}), where η is the power of multifractal intensity correlations. Thus, strong disorder typically increases the sensitivity of a system to an added impurity exponentially. We recover, on the metallic side of the transition, Anderson's result that the fidelity F decays with a power law F∼L^{-q(E_{F})} with system size L. Its power increases as the Fermi energy E_{F} approaches the mobility edge E_{M} as q(E_{F})∼[(E_{F}-E_{M})/E_{M}]^{-νη}, where ν is the critical exponent of the correlation length ξ_{c}. On the insulating side of the transition, F is constant for system sizes exceeding the localization length ξ. While these results are obtained for the typical fidelity F, we find that logF is widely, log normally, distributed with a width diverging at the AMIT. As a consequence, the mean value of the fidelity F converges to one at the AMIT, in strong contrast to its typical value which converges to zero exponentially fast with system size L. This counterintuitive behavior is explained as a manifestation of multifractality at the AMIT.
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Affiliation(s)
- S Kettemann
- School of Engineering and Science, Jacobs University, Campus Ring 1, 28759 Bremen, Germany and Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Nam-gu, Pohang 790-784, South Korea
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16
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Petrović AP, Ansermet D, Chernyshov D, Hoesch M, Salloum D, Gougeon P, Potel M, Boeri L, Panagopoulos C. A disorder-enhanced quasi-one-dimensional superconductor. Nat Commun 2016; 7:12262. [PMID: 27448209 PMCID: PMC4961838 DOI: 10.1038/ncomms12262] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 06/17/2016] [Indexed: 12/01/2022] Open
Abstract
A powerful approach to analysing quantum systems with dimensionality d>1 involves adding a weak coupling to an array of one-dimensional (1D) chains. The resultant quasi-1D (q1D) systems can exhibit long-range order at low temperature, but are heavily influenced by interactions and disorder due to their large anisotropies. Real q1D materials are therefore ideal candidates not only to provoke, test and refine theories of strongly correlated matter, but also to search for unusual emergent electronic phases. Here we report the unprecedented enhancement of a superconducting instability by disorder in single crystals of Na2−δMo6Se6, a q1D superconductor comprising MoSe chains weakly coupled by Na atoms. We argue that disorder-enhanced Coulomb pair-breaking (which usually destroys superconductivity) may be averted due to a screened long-range Coulomb repulsion intrinsic to disordered q1D materials. Our results illustrate the capability of disorder to tune and induce new correlated electron physics in low-dimensional materials. Disorder localizes electrons, which is usually detrimental to the onset of superconductivity. Here, Petrović et al. report a disorder-enhanced superconducting instability in quasi-one dimensional Na2-dMo6Se6 and suggest that this effect may originate from an intrinsically screened Coulomb repulsion.
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Affiliation(s)
- A P Petrović
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore
| | - D Ansermet
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore
| | - D Chernyshov
- Swiss-Norwegian Beamlines, European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble Cedex, France
| | - M Hoesch
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, Oxfordshire, UK
| | - D Salloum
- Sciences Chimiques, CSM UMR CNRS 6226, Université de Rennes 1, Avenue du Général Leclerc, 35042 Rennes Cedex, France.,Faculty of Science III, Lebanese University, PO Box 826, Kobbeh-Tripoli, Lebanon
| | - P Gougeon
- Sciences Chimiques, CSM UMR CNRS 6226, Université de Rennes 1, Avenue du Général Leclerc, 35042 Rennes Cedex, France
| | - M Potel
- Sciences Chimiques, CSM UMR CNRS 6226, Université de Rennes 1, Avenue du Général Leclerc, 35042 Rennes Cedex, France
| | - L Boeri
- Institute for Theoretical and Computational Physics, TU Graz, Petersgasse 16, 8010 Graz, Austria
| | - C Panagopoulos
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore
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17
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Kamar NA, Vidhyadhiraja NS. Site-disorder driven superconductor-insulator transition: a dynamical mean field study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:095701. [PMID: 24525620 DOI: 10.1088/0953-8984/26/9/095701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We investigate the effect of site disorder on the superconducting state in the attractive Hubbard model within the framework of dynamical mean field theory. For a fixed interaction strength (U), the superconducting order parameter decreases monotonically with increasing disorder (x), while the single-particle spectral gap decreases for small x, reaches a minimum and keeps increasing for larger x. Thus, the system remains gapped beyond the destruction of the superconducting state, indicating a disorder-driven superconductor-insulator transition. We investigate this transition in depth considering the effects of weak and strong disorder for a range of interaction strengths. In the clean case, the order parameter is known to increase monotonically with increasing interaction, saturating at a finite value asymptotically for U→∞. The presence of disorder results in destruction of superconductivity at large U, thus drastically modifying the clean case behaviour. A physical understanding of our findings is obtained by invoking particle-hole asymmetry and the probability distributions of the order parameter and spectral gap.
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Affiliation(s)
- Naushad Ahmad Kamar
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India
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18
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Ghosh S, Mandal SS. Amplitude fluctuations driven by the density of electron pairs within nanosize granular structures inside strongly disordered superconductors: evidence for a shell-like effect. PHYSICAL REVIEW LETTERS 2013; 111:207004. [PMID: 24289705 DOI: 10.1103/physrevlett.111.207004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Indexed: 06/02/2023]
Abstract
Motivated by the recent observation of the shell effect in a nanoscale pure superconductor by Bose et al. [Nat. Mater. 9, 550 (2010)], we explore the possible shell-like effect in a strongly disordered superconductor as it is known to produce nanosize superconducting puddles (SPs). We find a remarkable change in the texture of the pairing amplitudes that is responsible for forming the SP, upon monotonic tuning of the average electron density, <n>, and keeping the disorder landscape unaltered. Both the spatially averaged pairing amplitude and the quasiparticle excitation gap oscillate with <n>. This oscillation is due to a rapid change in the low-lying quasiparticle energy spectra and thereby a change in the shapes and positions of the SPs. We establish a correlation between the formation of SPs and the shell-like effect. The experimental consequences of our theory are also discussed.
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Affiliation(s)
- Sanjib Ghosh
- Department of Theoretical Physics, Indian Association for the Cultivation of Science, Kolkata 700 032, India
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19
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Kamlapure A, Das T, Ganguli SC, Parmar JB, Bhattacharyya S, Raychaudhuri P. Emergence of nanoscale inhomogeneity in the superconducting state of a homogeneously disordered conventional superconductor. Sci Rep 2013; 3:2979. [PMID: 24132046 PMCID: PMC3797984 DOI: 10.1038/srep02979] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 10/02/2013] [Indexed: 11/09/2022] Open
Abstract
The notion of spontaneous formation of an inhomogeneous superconducting state is at the heart of most theories attempting to understand the superconducting state in the presence of strong disorder. Using scanning tunneling spectroscopy and high resolution scanning transmission electron microscopy, we experimentally demonstrate that under the competing effects of strong homogeneous disorder and superconducting correlations, the superconducting state of a conventional superconductor, NbN, spontaneously segregates into domains. Tracking these domains as a function of temperature we observe that the superconducting domains persist across the bulk superconducting transition, Tc, and disappear close to the pseudogap temperature, T*, where signatures of superconducting correlations disappear from the tunneling spectrum and the superfluid response of the system.
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Affiliation(s)
- Anand Kamlapure
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
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20
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Burmistrov IS, Gornyi IV, Mirlin AD. Multifractality at Anderson transitions with Coulomb interaction. PHYSICAL REVIEW LETTERS 2013; 111:066601. [PMID: 23971596 DOI: 10.1103/physrevlett.111.066601] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Indexed: 05/06/2023]
Abstract
We explore mesoscopic fluctuations and correlations of the local density of states (LDOS) near localization transition in a disordered interacting electronic system. It is shown that the LDOS multifractality survives in the presence of the Coulomb interaction. We calculate the spectrum of multifractal dimensions in 2+ϵ spatial dimensions and show that it differs from that in the absence of interaction. The multifractal character of fluctuations and correlations of the LDOS can be studied experimentally by scanning tunneling microscopy of two-dimensional and three-dimensional disordered structures.
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Affiliation(s)
- I S Burmistrov
- L.D. Landau Institute for Theoretical Physics, Kosygina Street 2, 119334 Moscow, Russia
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21
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Lo ST, Chen KY, Lin SD, Wu JY, Lin TL, Yeh MR, Chen TM, Liang CT. Controllable disorder in a hybrid nanoelectronic system: realization of a superconducting diode. Sci Rep 2013; 3:2274. [PMID: 23881449 PMCID: PMC3721077 DOI: 10.1038/srep02274] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 07/08/2013] [Indexed: 11/09/2022] Open
Abstract
We have studied a hybrid nanoelectronic system which consists of an AlGaAs/GaAs two-dimensional electron gas (2DEG) in close proximity (~70 nm) to an Al superconducting nanofilm. By tuning the current through the Al film, we can change the conductance of the 2DEG and furthermore vary the effective disorder in the Al superconducting film in a controllable way. When a high current is injected into the film, screening which couples the Al film and the 2DEG results in a collapse of anti-symmetric behavior in the current-voltage characteristics, V(I) ~ -V(-I), which holds true in a conventional superconductor. Our results may open a new avenue of experimentally realizing a superconducting diode.
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Affiliation(s)
- Shun-Tsung Lo
- Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan
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22
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Foster MS, Yuzbashyan EA. Interaction-mediated surface-state instability in disordered three-dimensional topological superconductors with spin SU2 symmetry. PHYSICAL REVIEW LETTERS 2012; 109:246801. [PMID: 23368360 DOI: 10.1103/physrevlett.109.246801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Indexed: 06/01/2023]
Abstract
We show that arbitrarily weak interparticle interactions destabilize the surface states of 3D topological superconductors with spin SU(2) invariance (symmetry class CI) in the presence of nonmagnetic disorder. The conduit for the instability is disorder-induced wave function multifractality. We argue that time-reversal symmetry breaks spontaneously at the surface, so that topologically protected states do not exist for this class. The interaction-stabilized surface phase is expected to exhibit ferromagnetic order, or to reside in an insulating plateau of the spin quantum Hall effect.
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Affiliation(s)
- Matthew S Foster
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
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23
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Cuevas E, Feigel'man M, Ioffe L, Mezard M. Level statistics of disordered spin-1/2 systems and materials with localized Cooper pairs. Nat Commun 2012; 3:1128. [DOI: 10.1038/ncomms2115] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 09/05/2012] [Indexed: 11/09/2022] Open
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24
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Kravtsov VE, Yevtushenko OM, Snajberk P, Cuevas E. Lévy flights and multifractality in quantum critical diffusion and in classical random walks on fractals. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:021136. [PMID: 23005751 DOI: 10.1103/physreve.86.021136] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Indexed: 06/01/2023]
Abstract
We employ the method of virial expansion to compute the retarded density correlation function (generalized diffusion propagator) in the critical random matrix ensemble in the limit of strong multifractality. We find that the long-range nature of the Hamiltonian is a common root of both multifractality and Lévy flights, which show up in the power-law intermediate- and long-distance behaviors, respectively, of the density correlation function. We review certain models of classical random walks on fractals and show the similarity of the density correlation function in them to that for the quantum problem described by the random critical long-range Hamiltonians.
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Affiliation(s)
- V E Kravtsov
- The Abdus Salam International Centre for Theoretical Physics, PO Box 586, 34100 Trieste, Italy
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25
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Seibold G, Benfatto L, Castellani C, Lorenzana J. Superfluid density and phase relaxation in superconductors with strong disorder. PHYSICAL REVIEW LETTERS 2012; 108:207004. [PMID: 23003178 DOI: 10.1103/physrevlett.108.207004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2011] [Revised: 02/18/2012] [Indexed: 06/01/2023]
Abstract
We consider the attractive Hubbard model with on-site disorder as a prototype of a disordered superconductor. We solve the Bogoliubov-de Gennes equations on two-dimensional finite clusters at zero temperature and evaluate the electromagnetic response to a vector potential. We find that the standard decoupling between transverse and longitudinal response does not apply in the presence of disorder. Moreover, the superfluid density is strongly reduced by the relaxation of the phase of the order parameter already at mean-field level when disorder is large. We also find that the anharmonicity of the phase fluctuations is strongly enhanced by disorder. Beyond mean field, this provides an enhancement of quantum fluctuations inducing a zero-temperature transition to a nonsuperconducting phase of disordered preformed pairs. Finally, the connection of our findings with the glassy physics for extreme dirty superconductors is discussed.
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Affiliation(s)
- G Seibold
- Institut Für Physik, BTU Cottbus, PostBox 101344, 03013 Cottbus, Germany
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26
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Astafiev OV, Ioffe LB, Kafanov S, Pashkin YA, Arutyunov KY, Shahar D, Cohen O, Tsai JS. Coherent quantum phase slip. Nature 2012; 484:355-8. [PMID: 22517162 DOI: 10.1038/nature10930] [Citation(s) in RCA: 193] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 02/03/2012] [Indexed: 11/09/2022]
Abstract
A hundred years after the discovery of superconductivity, one fundamental prediction of the theory, coherent quantum phase slip (CQPS), has not been observed. CQPS is a phenomenon exactly dual to the Josephson effect; whereas the latter is a coherent transfer of charges between superconducting leads, the former is a coherent transfer of vortices or fluxes across a superconducting wire. In contrast to previously reported observations of incoherent phase slip, CQPS has been only a subject of theoretical study. Its experimental demonstration is made difficult by quasiparticle dissipation due to gapless excitations in nanowires or in vortex cores. This difficulty might be overcome by using certain strongly disordered superconductors near the superconductor-insulator transition. Here we report direct observation of CQPS in a narrow segment of a superconducting loop made of strongly disordered indium oxide; the effect is made manifest through the superposition of quantum states with different numbers of flux quanta. As with the Josephson effect, our observation should lead to new applications in superconducting electronics and quantum metrology.
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Affiliation(s)
- O V Astafiev
- NEC Green Innovation Research Laboratories, 34 Miyukigaoka, Tsukuba, Ibaraki, 305-8501, Japan.
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27
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Burmistrov IS, Gornyi IV, Mirlin AD. Enhancement of the critical temperature of superconductors by Anderson localization. PHYSICAL REVIEW LETTERS 2012; 108:017002. [PMID: 22304280 DOI: 10.1103/physrevlett.108.017002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Indexed: 05/31/2023]
Abstract
The influence of disorder on the temperature of superconducting transition (T{c}) is studied within the σ-model renormalization-group framework. Electron-electron interaction in particle-hole and Cooper channels is taken into account and assumed to be short range. Two-dimensional systems in the weak localization and antilocalization regime, as well as systems near mobility edge are considered. It is shown that in all these regimes Anderson localization leads to strong enhancement of T{c} related to the multifractality of wave functions. Screening of the long-range Coulomb interaction thus opens a promising direction for searching novel materials for high-T{c} superconductivity.
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Affiliation(s)
- I S Burmistrov
- L.D. Landau Institute for Theoretical Physics, Kosygina street 2, 117940 Moscow, Russia
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28
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Lin YH, Goldman AM. Magnetic-field-tuned quantum phase transition in the insulating regime of ultrathin amorphous Bi films. PHYSICAL REVIEW LETTERS 2011; 106:127003. [PMID: 21517344 DOI: 10.1103/physrevlett.106.127003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 01/28/2011] [Indexed: 05/30/2023]
Abstract
A surprisingly strong variation of resistance with a perpendicular magnetic field, and a peak in the resistance versus field, R(B) has been found in insulating films of a sequence of homogeneous, quench-condensed films of amorphous Bi undergoing a thickness-tuned superconductor-insulator transition. Isotherms of magnetoresistance, rather than resistance, versus field were found to cross at a well-defined magnetic field higher than the field corresponding to the peak in R(B). For all values of B, R(T) was found to obey an Arrhenius form. At the crossover magnetic field the prefactor became equal to the quantum resistance of electron pairs h/4e², and the activation energy returned to its zero-field value. These observations suggest that the crossover is the signature of a quantum phase transition between two distinct insulating ground states, tuned by magnetic field.
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Affiliation(s)
- Yen-Hsiang Lin
- School of Physics and Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, Minnesota 55455, USA
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29
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Mondal M, Kamlapure A, Chand M, Saraswat G, Kumar S, Jesudasan J, Benfatto L, Tripathi V, Raychaudhuri P. Phase fluctuations in a strongly disordered s-wave NbN superconductor close to the metal-insulator transition. PHYSICAL REVIEW LETTERS 2011; 106:047001. [PMID: 21405347 DOI: 10.1103/physrevlett.106.047001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2010] [Indexed: 05/30/2023]
Abstract
We explore the role of phase fluctuations in a three-dimensional s-wave superconductor, NbN, as we approach the critical disorder for destruction of the superconducting state. Close to critical disorder, we observe a finite gap in the electronic spectrum which persists at temperatures well above T(c). The superfluid density is strongly suppressed at low temperatures and evolves towards a linear-T variation at higher temperatures. These observations provide strong evidence that phase fluctuations play a central role in the formation of a pseudogap state in a disordered s-wave superconductor.
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Affiliation(s)
- Mintu Mondal
- Tata Institute of Fundamental Research, Mumbai, India
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30
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Ioffe LB, Mézard M. Disorder-driven quantum phase transitions in superconductors and magnets. PHYSICAL REVIEW LETTERS 2010; 105:037001. [PMID: 20867791 DOI: 10.1103/physrevlett.105.037001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Indexed: 05/29/2023]
Abstract
We develop an analytical theory, based on the quantum cavity method, describing the quantum phase transitions in low-temperature, strongly disordered ferromagnets and superconductors. At variance with the usual quantum critical points, we find a phase diagram with two critical points separating three phases. When the disorder increases, the systems goes from the ordered phase to an intermediate disordered phase characterized by activated transport and then to a second disordered phase where no transport is possible. Both the ordered and disordered phases exhibit strong inhomogeneity of their basic properties typical of glassy physics.
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Affiliation(s)
- L B Ioffe
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
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31
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Nguyen HQ, Hollen SM, Stewart MD, Shainline J, Yin A, Xu JM, Valles JM. Observation of giant positive magnetoresistance in a Cooper pair insulator. PHYSICAL REVIEW LETTERS 2009; 103:157001. [PMID: 19905659 DOI: 10.1103/physrevlett.103.157001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 09/18/2009] [Indexed: 05/28/2023]
Abstract
Ultrathin amorphous Bi films, patterned with a nanohoneycomb array of holes, can exhibit an insulating phase with transport dominated by the incoherent motion of Cooper pairs (CP) of electrons between localized states. Here, we show that the magnetoresistance (MR) of this Cooper pair insulator (CPI) phase is positive and grows exponentially with decreasing temperature T, for T well below the pair formation temperature. It peaks at a field estimated to be sufficient to break the pairs and then decreases monotonically into a regime in which the film resistance assumes the T dependence appropriate for weakly localized single electron transport. We discuss how these results support proposals that the large MR peaks in other unpatterned, ultrathin film systems disclose a CPI phase and provide new insight into the CP localization.
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Affiliation(s)
- H Q Nguyen
- Department of Physics, Brown University, Providence, Rhode Island 02912, USA
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32
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Bose S, Galande C, Chockalingam SP, Banerjee R, Raychaudhuri P, Ayyub P. Competing effects of surface phonon softening and quantum size effects on the superconducting properties of nanostructured Pb. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:205702. [PMID: 21825535 DOI: 10.1088/0953-8984/21/20/205702] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The superconducting transition temperature (T(C)) in nanostructured Pb decreases from 7.24 to 6.4 K as the particle size is reduced from 65 to 7 nm, below which superconductivity is lost rather abruptly. In contrast, there is a large enhancement in the upper critical field (H(C2)) in the same size regime. We explore the origin of the unusual robustness of T(C) over such a large particle size range in nanostructured Pb by measuring the temperature dependence of the superconducting energy gap in planar tunnel junctions of Al/Al(2)O(3)/nano-Pb. We show that below 22 nm, the electron-phonon coupling strength increases monotonically with decreasing particle size, and almost exactly compensates for the quantum size effect, which is expected to suppress T(C).
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Affiliation(s)
- Sangita Bose
- Department of Condensed Matter Physics and Material Science, Tata Institute of Fundamental Research, Mumbai 400005, India
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33
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Blase X, Bustarret E, Chapelier C, Klein T, Marcenat C. Superconducting group-IV semiconductors. NATURE MATERIALS 2009; 8:375-382. [PMID: 19387452 DOI: 10.1038/nmat2425] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Despite the amount of experimental and theoretical work on doping-induced superconductivity in covalent semiconductors based on group IV elements over the past four years, many open questions and puzzling results remain to be clarified. The nature of the coupling (whether mediated by electronic correlation, phonons or both), the relationship between the doping concentration and the critical temperature (T(c)), which affects the prospects for higher transition temperatures, and the influence of disorder and dopant homogeneity are debated issues that will determine the future of the field. Here, we present recent achievements and predictions, with a focus on boron-doped diamond and silicon. We also suggest that innovative superconducting devices, combining specific properties of diamond or silicon with the maturity of semiconductor-based technologies, will soon be developed.
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Affiliation(s)
- Xavier Blase
- Institut Néel, CNRS and Université Joseph Fourier, BP 166, 38042 Grenoble Cedex 9, France.
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34
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Yanase Y, Yorozu N. Superconductivity in compensated and uncompensated semiconductors. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2008; 9:044201. [PMID: 27878018 PMCID: PMC5099632 DOI: 10.1088/1468-6996/9/4/044201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Revised: 01/28/2009] [Accepted: 11/06/2008] [Indexed: 05/31/2023]
Abstract
We investigate the localization and superconductivity in heavily doped semiconductors. The crossover from the superconductivity in the host band to that in the impurity band is described on the basis of the disordered three-dimensional attractive Hubbard model for binary alloys. The microscopic inhomogeneity and the thermal superconducting fluctuation are taken into account using the self-consistent 1-loop order theory. The superconductor-insulator transition accompanies the crossover from the host band to the impurity band. We point out an enhancement of the critical temperature Tc around the crossover. Further localization of electron wave functions leads to the localization of Cooper pairs and induces the pseudogap. We find that both the doping compensation by additional donors and the carrier increase by additional acceptors suppress the superconductivity. A theoretical interpretation is proposed for the superconductivity in the boron-doped diamond, SiC, and Si.
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Affiliation(s)
- Youichi Yanase
- Department of Physics, University of Tokyo, Tokyo 113-0033, Japan
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35
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Sacépé B, Chapelier C, Baturina TI, Vinokur VM, Baklanov MR, Sanquer M. Disorder-induced inhomogeneities of the superconducting state close to the superconductor-insulator transition. PHYSICAL REVIEW LETTERS 2008; 101:157006. [PMID: 18999631 DOI: 10.1103/physrevlett.101.157006] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Indexed: 05/27/2023]
Abstract
Scanning tunneling spectroscopy at very low temperatures on homogeneously disordered superconducting titanium nitride thin films reveals strong spatial inhomogeneities of the superconducting gap Delta in the density of states. Upon increasing disorder, we observe suppression of the superconducting critical temperature Tc towards zero, enhancement of spatial fluctuations in Delta, and growth of the Delta/Tc ratio. These findings suggest that local superconductivity survives across the disorder-driven superconductor-insulator transition.
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Affiliation(s)
- B Sacépé
- CEA, INAC, SPSMS-LaTEQS, 38054 Grenoble, France
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