51
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Yazdani-Kachoei M, Jalali-Asadabadi S, Ahmad I, Zarringhalam K. Pressure dependency of localization degree in heavy fermion CeIn3: A density functional theory analysis. Sci Rep 2016; 6:31734. [PMID: 27553428 PMCID: PMC4995468 DOI: 10.1038/srep31734] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 07/22/2016] [Indexed: 11/09/2022] Open
Abstract
Two dramatic discrepancies between previous reliable experimental and ab initio DFT results are identified to occur at two different pressures in CeIn3, as discussed through the paper. We physically discuss sources of the phenomena and indicate how to select an appropriate functional for a given pressure. We show that these discrepancies are due to the inaccuracy of the DFT + U scheme with arbitrary Ueff and that hybrid functionals can provide better agreement with experimental data at zero pressure. The hybrid B3PW91 approach provides much better agreement with experimental data than the GGA + U. The DFT + U scheme proves to be rather unreliable since it yields completely unpredictable oscillations for the bulk modulus with increasing values of Ueff. Our B3PW91 results show that the best lattice parameter (bulk modulus) is obtained using a larger value of α parameter, 0.4 (0.3 or 0.2), than that of usually considered for the AFM phase. We find that for hybrid functionals, the amount of non-local exchange must first be calibrated before conclusions are drawn. Therefore, we first systematically optimize the α parameter and using it investigate the magnetic and electronic properties of the system. We present a theoretical interpretation of the experimental results and reproduce them satisfactorily.
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Affiliation(s)
- M Yazdani-Kachoei
- Department of Physics, Faculty of Sciences, University of Isfahan (UI), Hezar Gerib Avenue, Isfahan 81746-73441, Iran
| | - S Jalali-Asadabadi
- Department of Physics, Faculty of Sciences, University of Isfahan (UI), Hezar Gerib Avenue, Isfahan 81746-73441, Iran
| | - Iftikhar Ahmad
- Center for Computational Materials Science, University of Malakand, Chakdara, Pakistan.,bbottabad University of Science and Technology, Havelian, Pakistan
| | - Kourosh Zarringhalam
- Department of Mathematics, University of Massachusetts Boston, Boston, MA 02125, USA
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52
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Jungwirth T, Marti X, Wadley P, Wunderlich J. Antiferromagnetic spintronics. NATURE NANOTECHNOLOGY 2016; 11:231-41. [PMID: 26936817 DOI: 10.1038/nnano.2016.18] [Citation(s) in RCA: 445] [Impact Index Per Article: 55.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 01/25/2016] [Indexed: 05/22/2023]
Abstract
Antiferromagnetic materials are internally magnetic, but the direction of their ordered microscopic moments alternates between individual atomic sites. The resulting zero net magnetic moment makes magnetism in antiferromagnets externally invisible. This implies that information stored in antiferromagnetic moments would be invisible to common magnetic probes, insensitive to disturbing magnetic fields, and the antiferromagnetic element would not magnetically affect its neighbours, regardless of how densely the elements are arranged in the device. The intrinsic high frequencies of antiferromagnetic dynamics represent another property that makes antiferromagnets distinct from ferromagnets. Among the outstanding questions is how to manipulate and detect the magnetic state of an antiferromagnet efficiently. In this Review we focus on recent works that have addressed this question. The field of antiferromagnetic spintronics can also be viewed from the general perspectives of spin transport, magnetic textures and dynamics, and materials research. We briefly mention this broader context, together with an outlook of future research and applications of antiferromagnetic spintronics.
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Affiliation(s)
- T Jungwirth
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 53 Praha 6, Czech Republic
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - X Marti
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - P Wadley
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - J Wunderlich
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 53 Praha 6, Czech Republic
- Hitachi Cambridge Laboratory, Cambridge CB3 0HE, UK
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53
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Pressure dependence of electronic structure and superconductivity of the MnX (X = N, P, As, Sb). Sci Rep 2016; 6:21821. [PMID: 26902857 PMCID: PMC4763175 DOI: 10.1038/srep21821] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 02/01/2016] [Indexed: 11/09/2022] Open
Abstract
A recently experimental discovered (Cheng et al., Phys. Rev. Lett. 114, 117001 (2015)) of superconductivity on the border of long-range magnetic order in the itinerant-electron helimagnet MnP via the application of high pressure makes MnP the first Mn-based superconductor. In this paper, we carry out first-principles calculations on MnX (X = N, P, As, Sb) and find superconducting critical temperature TC of MnP sharply increases near the critical pressure PC ≈ 8 GPa, which is in good agreement with the experiments. Electron-phonon coupling constant λ and electronic density of states at the Fermi level N (EF) are found to increase with pressure for MnP, which lead to the increase of TC of MnP. Moreover, we also find that the TC of MnAs and MnSb are higher than MnP, implying that the MnAs and MnSb may be the more potential Mn-based superconducting materials.
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Aggarwal L, Gaurav A, Thakur GS, Haque Z, Ganguli AK, Sheet G. Unconventional superconductivity at mesoscopic point contacts on the 3D Dirac semimetal Cd3As2. NATURE MATERIALS 2016; 15:32-37. [PMID: 26524131 DOI: 10.1038/nmat4455] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 08/13/2015] [Indexed: 06/05/2023]
Abstract
Three-dimensional (3D) Dirac semimetals exist close to topological phase boundaries which, in principle, should make it possible to drive them into exotic new phases, such as topological superconductivity, by breaking certain symmetries. A practical realization of this idea has, however, hitherto been lacking. Here we show that the mesoscopic point contacts between pure silver (Ag) and the 3D Dirac semimetal Cd3As2 (ref. ) exhibit unconventional superconductivity with a critical temperature (onset) greater than 6 K whereas neither Cd3As2 nor Ag are superconductors. A gap amplitude of 6.5 meV is measured spectroscopically in this phase that varies weakly with temperature and survives up to a remarkably high temperature of 13 K, indicating the presence of a robust normal-state pseudogap. The observations indicate the emergence of a new unconventional superconducting phase that exists in a quantum mechanically confined region under a point contact between a Dirac semimetal and a normal metal.
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Affiliation(s)
- Leena Aggarwal
- Department of Physical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Sector 81, S. A. S. Nagar Manauli, PO 140306, India
| | - Abhishek Gaurav
- Department of Physical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Sector 81, S. A. S. Nagar Manauli, PO 140306, India
| | - Gohil S Thakur
- Department of Chemistry, Indian Institute of Technology, New Delhi 110016, India
| | - Zeba Haque
- Department of Chemistry, Indian Institute of Technology, New Delhi 110016, India
| | - Ashok K Ganguli
- Department of Chemistry, Indian Institute of Technology, New Delhi 110016, India
- Institute of Nano Science and Technology, Mohali 160064, India
| | - Goutam Sheet
- Department of Physical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Sector 81, S. A. S. Nagar Manauli, PO 140306, India
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55
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Murmann S, Deuretzbacher F, Zürn G, Bjerlin J, Reimann SM, Santos L, Lompe T, Jochim S. Antiferromagnetic Heisenberg Spin Chain of a Few Cold Atoms in a One-Dimensional Trap. PHYSICAL REVIEW LETTERS 2015; 115:215301. [PMID: 26636858 DOI: 10.1103/physrevlett.115.215301] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Indexed: 06/05/2023]
Abstract
We report on the deterministic preparation of antiferromagnetic Heisenberg spin chains consisting of up to four fermionic atoms in a one-dimensional trap. These chains are stabilized by strong repulsive interactions between the two spin components without the need for an external periodic potential. We independently characterize the spin configuration of the chains by measuring the spin orientation of the outermost particle in the trap and by projecting the spatial wave function of one spin component on single-particle trap levels. Our results are in good agreement with a spin-chain model for fermionized particles and with numerically exact diagonalizations of the full few-fermion system.
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Affiliation(s)
- S Murmann
- Physikalisches Institut der Universität Heidelberg, Im Neuenheimer Feld 226, DE-69120 Heidelberg, Germany
| | - F Deuretzbacher
- Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstraße 2, DE-30167 Hannover, Germany
| | - G Zürn
- Physikalisches Institut der Universität Heidelberg, Im Neuenheimer Feld 226, DE-69120 Heidelberg, Germany
| | - J Bjerlin
- Mathematical Physics and NanoLund, LTH, Lund University, SE-22100 Lund, Sweden
| | - S M Reimann
- Mathematical Physics and NanoLund, LTH, Lund University, SE-22100 Lund, Sweden
| | - L Santos
- Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstraße 2, DE-30167 Hannover, Germany
| | - T Lompe
- Physikalisches Institut der Universität Heidelberg, Im Neuenheimer Feld 226, DE-69120 Heidelberg, Germany
| | - S Jochim
- Physikalisches Institut der Universität Heidelberg, Im Neuenheimer Feld 226, DE-69120 Heidelberg, Germany
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56
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Kang M, Wakeham N, Ni N, Bauer ED, Kim J, Ronning F. Thermal and transport properties of U2Pt(x)Ir(1-x)C2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:365702. [PMID: 26302330 DOI: 10.1088/0953-8984/27/36/365702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report thermal and transport properties of U2Pt x Ir1-x C2 from which a magnetic phase diagram is obtained. Pure U2IrC2 is an antiferromagnet at 6.5 K, whose Néel temperature initially rises to 13.2 K at x = 0.2 and subsequently is suppressed to zero temperature with increasing Pt content near x = 0.6. Heat capacity divided by temperature at x = 0.6 shows an upturn at low temperature, consistent with the expectations of enhanced quantum fluctuations in the presence of an underlying quantum critical point. The entropy after the phonon contribution has been subtracted has a value of 0.24 Rln2 at the Néel temperature of U2IrC2, revealing an itinerant nature of the 5 f electrons in this compound. On the Pt rich side of the phase diagram, superconductivity is suppressed by x = 0.85. The residual resistivity increases by a factor of 10 from pure Pt (x = 1) to x = 0.85 where superconductivity is suppressed to zero. By comparing the phase diagram of Ir doped U2PtC2 with the phase diagram of pressure tuned and Rh doped U2PtC2 we demonstrate the role of electronic tuning in this system.
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Affiliation(s)
- Mingu Kang
- CALDES, Institute of Basic Science, Pohang, Gyeongbuk 790-784, Korea. Department of Physics, Pohang University of Science and Technology (POSTECH) Pohang, Gyeongbuk 790-784, Korea. Los Alamos National Laboratory, Materials Physics and Applications Division, Los Alamos, NM 87545, USA
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57
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Böhmer AE, Hardy F, Wang L, Wolf T, Schweiss P, Meingast C. Superconductivity-induced re-entrance of the orthorhombic distortion in Ba1-xKxFe2As2. Nat Commun 2015; 6:7911. [PMID: 26227915 PMCID: PMC4532874 DOI: 10.1038/ncomms8911] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 06/22/2015] [Indexed: 11/28/2022] Open
Abstract
Detailed knowledge of the phase diagram and the nature of the competing magnetic and superconducting phases is imperative for a deeper understanding of the physics of iron-based superconductivity. Magnetism in the iron-based superconductors is usually a stripe-type spin-density-wave, which breaks the tetragonal symmetry of the lattice, and is known to compete strongly with superconductivity. Recently, it was found that in some systems an additional spin-density-wave transition occurs, which restores this tetragonal symmetry, however, its interaction with superconductivity remains unclear. Here, using thermodynamic measurements on Ba1−xKxFe2As2 single crystals, we show that the spin-density-wave phase of tetragonal symmetry competes much stronger with superconductivity than the stripe-type spin-density-wave phase, which results in a novel re-entrance of the latter at or slightly below the superconducting transition. The interplay between magnetic and superconducting phases is important to understand the physics of iron-based superconductivity. Here, the authors use thermodynamic measurements on Ba1−xKxFe2As2 single crystals to provide details of its phase diagram and the re-entrance of a C2 spin-density-wave phase.
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Affiliation(s)
- A E Böhmer
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - F Hardy
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - L Wang
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - T Wolf
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - P Schweiss
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - C Meingast
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
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58
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Di Sabatino S, Berger JA, Reining L, Romaniello P. Reduced density-matrix functional theory: Correlation and spectroscopy. J Chem Phys 2015; 143:024108. [DOI: 10.1063/1.4926327] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- S. Di Sabatino
- Laboratoire de Physique Théorique, CNRS, IRSAMC, Université Toulouse III–Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex, France and ETSF
| | - J. A. Berger
- Laboratoire de Chimie et Physique Quantiques, IRSAMC, Université Toulouse III–Paul Sabatier, CNRS, 118 Route de Narbonne, 31062 Toulouse Cedex, France and ETSF
| | - L. Reining
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA-DSM, 91128 Palaiseau, France and ETSF
| | - P. Romaniello
- Laboratoire de Physique Théorique, CNRS, IRSAMC, Université Toulouse III–Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex, France and ETSF
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59
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Magnetic moment formation due to arsenic vacancies in LaFeAsO-derived superconductors. Sci Rep 2015; 5:11280. [PMID: 26169486 PMCID: PMC4501002 DOI: 10.1038/srep11280] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 05/07/2015] [Indexed: 11/09/2022] Open
Abstract
Arsenic vacancies in LaFeAsO-derived superconductors are nominally non-magnetic defects. However, we find from a microscopic theory in terms of an appropriately modified Anderson-Wolff model that in their vicinity local magnetic moments form. They can arise because removing an arsenic atom breaks four strong, covalent bonds with the neighboring iron atoms. The moments emerging around an arsenic vacancy orient ferromagnetically and cause a substantial enhancement of the paramagnetic susceptibility in both the normal and superconducting state. The qualitative model description is supported by first principles band structure calculations of the As-vacancy related defect spectrum within a larger supercell.
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60
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Zadik RH, Takabayashi Y, Klupp G, Colman RH, Ganin AY, Potočnik A, Jeglič P, Arčon D, Matus P, Kamarás K, Kasahara Y, Iwasa Y, Fitch AN, Ohishi Y, Garbarino G, Kato K, Rosseinsky MJ, Prassides K. Optimized unconventional superconductivity in a molecular Jahn-Teller metal. SCIENCE ADVANCES 2015; 1:e1500059. [PMID: 26601168 PMCID: PMC4640631 DOI: 10.1126/sciadv.1500059] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 03/12/2015] [Indexed: 05/30/2023]
Abstract
Understanding the relationship between the superconducting, the neighboring insulating, and the normal metallic state above T c is a major challenge for all unconventional superconductors. The molecular A3C60 fulleride superconductors have a parent antiferromagnetic insulator in common with the atom-based cuprates, but here, the C60 (3-) electronic structure controls the geometry and spin state of the structural building unit via the on-molecule Jahn-Teller effect. We identify the Jahn-Teller metal as a fluctuating microscopically heterogeneous coexistence of both localized Jahn-Teller-active and itinerant electrons that connects the insulating and superconducting states of fullerides. The balance between these molecular and extended lattice features of the electrons at the Fermi level gives a dome-shaped variation of T c with interfulleride separation, demonstrating molecular electronic structure control of superconductivity.
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Affiliation(s)
- Ruth H. Zadik
- Department of Chemistry, Durham University, Durham DH13LE, UK
| | | | - Gyöngyi Klupp
- Department of Chemistry, Durham University, Durham DH13LE, UK
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1525 Budapest, Hungary
| | - Ross H. Colman
- Department of Chemistry, Durham University, Durham DH13LE, UK
| | - Alexey Y. Ganin
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, UK
| | - Anton Potočnik
- Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
| | - Peter Jeglič
- Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
| | - Denis Arčon
- Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
| | - Péter Matus
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1525 Budapest, Hungary
| | - Katalin Kamarás
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1525 Budapest, Hungary
| | - Yuichi Kasahara
- Quantum-Phase Electronics Center and Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - Yoshihiro Iwasa
- Quantum-Phase Electronics Center and Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - Andrew N. Fitch
- European Synchrotron Radiation Facility, 38043 Grenoble, France
| | - Yasuo Ohishi
- Japan Synchrotron Radiation Research Institute, SPring-8, Hyogo 679-5198, Japan
| | | | - Kenichi Kato
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | | | - Kosmas Prassides
- Department of Chemistry, Durham University, Durham DH13LE, UK
- World Premier International–Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Japan Science and Technology Agency, ERATO Isobe Degenerate π-Integration Project, Tohoku University, Sendai 980-8577, Japan
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61
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Ong W, Cheng C, Arakelyan I, Thomas JE. Spin-imbalanced quasi-two-dimensional Fermi gases. PHYSICAL REVIEW LETTERS 2015; 114:110403. [PMID: 25839246 DOI: 10.1103/physrevlett.114.110403] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Indexed: 06/04/2023]
Abstract
We measure the density profiles for a Fermi gas of (6)Li containing N(1) spin-up atoms and N(2) spin-down atoms, confined in a quasi-two-dimensional geometry. The spatial profiles are measured as a function of spin imbalance N(2)/N(1) and interaction strength, which is controlled by means of a collisional (Feshbach) resonance. The measured cloud radii and central densities are in disagreement with mean-field Bardeen-Cooper-Schrieffer theory for a true two-dimensional system. We find that the data for normal-fluid mixtures are reasonably well fit by a simple two-dimensional polaron model of the free energy. Not predicted by the model is a phase transition to a spin-balanced central core, which is observed above a critical value of N(2)/N(1). Our observations provide important benchmarks for predictions of the phase structure of quasi-two-dimensional Fermi gases.
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Affiliation(s)
- W Ong
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
| | - Chingyun Cheng
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
| | - I Arakelyan
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - J E Thomas
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
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62
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Cheng JG, Matsubayashi K, Wu W, Sun JP, Lin FK, Luo JL, Uwatoko Y. Pressure induced superconductivity on the border of magnetic order in MnP. PHYSICAL REVIEW LETTERS 2015; 114:117001. [PMID: 25839302 DOI: 10.1103/physrevlett.114.117001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Indexed: 06/04/2023]
Abstract
We report the discovery of superconductivity on the border of long-range magnetic order in the itinerant-electron helimagnet MnP via the application of high pressure. Superconductivity with T(sc)≈1 K emerges and exists merely near the critical pressure P(c)≈8 GPa, where the long-range magnetic order just vanishes. The present finding makes MnP the first Mn-based superconductor. The close proximity of superconductivity to a magnetic instability suggests an unconventional pairing mechanism. Moreover, the detailed analysis of the normal-state transport properties evidenced non-Fermi-liquid behavior and the dramatic enhancement of the quasiparticle effective mass near P(c) associated with the magnetic quantum fluctuations.
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Affiliation(s)
- J-G Cheng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - K Matsubayashi
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - W Wu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - J P Sun
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - F K Lin
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - J L Luo
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Y Uwatoko
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
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63
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64
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Kim H, Tanatar MA, Flint R, Petrovic C, Hu R, White BD, Lum IK, Maple MB, Prozorov R. Nodal to nodeless superconducting energy-gap structure change concomitant with fermi-surface reconstruction in the heavy-fermion compound CeCoIn(5). PHYSICAL REVIEW LETTERS 2015; 114:027003. [PMID: 25635560 DOI: 10.1103/physrevlett.114.027003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Indexed: 06/04/2023]
Abstract
The London penetration depth λ(T) was measured in single crystals of Ce_{1-x}R_{x}CoIn_{5}, R=La, Nd, and Yb down to T_{min}≈50 mK (T_{c}/T_{min}∼50) using a tunnel-diode resonator. In the cleanest samples Δλ(T) is best described by the power law Δλ(T)∝T^{n}, with n∼1, consistent with the existence of line nodes in the superconducting gap. Substitutions of Ce with La, Nd, and Yb lead to similar monotonic suppressions of T_{c}; however, the effects on Δλ(T) differ. While La and Nd substitution leads to an increase in the exponent n and saturation at n∼2, as expected for a dirty nodal superconductor, Yb substitution leads to n>3, suggesting a change from nodal to nodeless superconductivity. This superconducting gap structure change happens in the same doping range where changes of the Fermi-surface topology were reported, implying that the nodal structure and Fermi-surface topology are closely linked.
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Affiliation(s)
- Hyunsoo Kim
- Ames Laboratory and Department of Physics & Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - M A Tanatar
- Ames Laboratory and Department of Physics & Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - R Flint
- Ames Laboratory and Department of Physics & Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - C Petrovic
- Department of Physics, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Rongwei Hu
- Department of Physics, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - B D White
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - I K Lum
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - M B Maple
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - R Prozorov
- Ames Laboratory and Department of Physics & Astronomy, Iowa State University, Ames, Iowa 50011, USA
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65
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Xu Z, Stock C, Chi S, Kolesnikov AI, Xu G, Gu G, Tranquada JM. Neutron-scattering evidence for a periodically modulated superconducting phase in the underdoped cuprate La1.905Ba0.095CuO4. PHYSICAL REVIEW LETTERS 2014; 113:177002. [PMID: 25379931 DOI: 10.1103/physrevlett.113.177002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Indexed: 06/04/2023]
Abstract
The role of antiferromagnetic spin correlations in high-temperature superconductors remains a matter of debate. We present inelastic neutron-scattering evidence that gapless spin fluctuations coexist with superconductivity in La1.905Ba0.095CuO4. Furthermore, we observe that both the low-energy magnetic spectral weight and the spin incommensurability are enhanced with the onset of superconducting correlations. We propose that the coexistence occurs through intertwining of spatial modulations of the pair wave function and the antiferromagnetic correlations. This proposal is also directly relevant to sufficiently underdoped La(2-x)Sr(x)CuO(4) and YBa(2)Cu(3)O(6+x).
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Affiliation(s)
- Zhijun Xu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - C Stock
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Songxue Chi
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - A I Kolesnikov
- Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Guangyong Xu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - Genda Gu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - J M Tranquada
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
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66
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Direct evidence for a magnetic f-electron-mediated pairing mechanism of heavy-fermion superconductivity in CeCoIn5. Proc Natl Acad Sci U S A 2014; 111:11663-7. [PMID: 25062692 DOI: 10.1073/pnas.1409444111] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To identify the microscopic mechanism of heavy-fermion Cooper pairing is an unresolved challenge in quantum matter studies; it may also relate closely to finding the pairing mechanism of high-temperature superconductivity. Magnetically mediated Cooper pairing has long been the conjectured basis of heavy-fermion superconductivity but no direct verification of this hypothesis was achievable. Here, we use a novel approach based on precision measurements of the heavy-fermion band structure using quasiparticle interference imaging to reveal quantitatively the momentum space (k-space) structure of the f-electron magnetic interactions of CeCoIn5. Then, by solving the superconducting gap equations on the two heavy-fermion bands Ek(α,β) with these magnetic interactions as mediators of the Cooper pairing, we derive a series of quantitative predictions about the superconductive state. The agreement found between these diverse predictions and the measured characteristics of superconducting CeCoIn5 then provides direct evidence that the heavy-fermion Cooper pairing is indeed mediated by f-electron magnetism.
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67
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Affiliation(s)
- Gunzi Saito
- Department of Agriculture, Meijo University, 1‐501 Shiogamaguchi, Tempaku‐ku, Nagoya 468‐8502, Japan, htpp://saitolab.meijo‐u.ac.jp
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68
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Schemm ER, Gannon WJ, Wishne CM, Halperin WP, Kapitulnik A. Observation of broken time-reversal symmetry in the heavy-fermion superconductor UPt3. Science 2014; 345:190-3. [DOI: 10.1126/science.1248552] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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69
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Meinert F, Mark MJ, Kirilov E, Lauber K, Weinmann P, Grobner M, Daley AJ, Nagerl HC. Observation of many-body dynamics in long-range tunneling after a quantum quench. Science 2014; 344:1259-62. [DOI: 10.1126/science.1248402] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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70
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Cai P, Ruan W, Zhou X, Ye C, Wang A, Chen X, Lee DH, Wang Y. Doping dependence of the anisotropic quasiparticle interference in NaFe(1-x)Co(x)As iron-based superconductors. PHYSICAL REVIEW LETTERS 2014; 112:127001. [PMID: 24724672 DOI: 10.1103/physrevlett.112.127001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Indexed: 06/03/2023]
Abstract
We use scanning tunneling microscopy to investigate the doping dependence of quasiparticle interference (QPI) in NaFe1-xCoxAs iron-based superconductors. The goal is to study the relation between nematic fluctuations and Cooper pairing. In the parent and underdoped compounds, where fourfold rotational symmetry is broken macroscopically, the QPI patterns reveal strong rotational anisotropy. At optimal doping, however, the QPI patterns are always fourfold symmetric. We argue this implies small nematic susceptibility and, hence, insignificant nematic fluctuation in optimally doped iron pnictides. Since TC is the highest this suggests nematic fluctuation is not a prerequistite for strong Cooper pairing.
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Affiliation(s)
- Peng Cai
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China and Collaborative Innovation Center of Quantum Matter, Beijing 100084, People's Republic of China
| | - Wei Ruan
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China and Collaborative Innovation Center of Quantum Matter, Beijing 100084, People's Republic of China
| | - Xiaodong Zhou
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China and Collaborative Innovation Center of Quantum Matter, Beijing 100084, People's Republic of China
| | - Cun Ye
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China and Collaborative Innovation Center of Quantum Matter, Beijing 100084, People's Republic of China
| | - Aifeng Wang
- Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Xianhui Chen
- Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Dung-Hai Lee
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA and Materials Science Division, Lawrence Berkeley National Lab, Berkeley, California 94720, USA
| | - Yayu Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China and Collaborative Innovation Center of Quantum Matter, Beijing 100084, People's Republic of China
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71
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Anisimov VI, Lukoyanov AV. Investigation of real materials with strong electronic correlations by the LDA+DMFT method. Acta Crystallogr C Struct Chem 2014; 70:137-59. [PMID: 24508959 DOI: 10.1107/s2053229613032312] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 11/20/2013] [Indexed: 11/10/2022] Open
Abstract
Materials with strong electronic correlations are at the cutting edge of experimental and theoretical studies, capturing the attention of researchers for a great variety of interesting phenomena: metal-insulator, phase and magnetic spin transitions, `heavy fermion' systems, interplay between magnetic order and superconductivity, appearance and disappearance of local magnetic moments, and transport property anomalies. It is clear that the richness of physical phenomena for these compounds is a result of partially filled 3d, 4f or 5f electron shells with local magnetic moments preserved in the solid state. Strong interactions of d and f electrons with each other and with itinerant electronic states of the material are responsible for its anomalous properties. Electronic structure calculations for strongly correlated materials should explicitly take into account Coulombic interactions between d or f electrons. Recent advances in this field are related to the development of the LDA+DMFT method, which combines local density approximation (LDA) with dynamical mean-field theory (DMFT) to account for electronic correlation effects. In recent years, LDA+DMFT has allowed the successful treatment not only of simple systems but also of complicated real compounds. Nowadays, the LDA+DMFT method is the state-of-the-art tool for investigating correlated metals and insulators, spin and metal-insulator transitions (MIT) in transition-metal compounds in paramagnetic and magnetically ordered phases.
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Affiliation(s)
- V I Anisimov
- Institute of Metal Physics, Russian Academy of Sciences, 620990 Yekaterinburg, Russia
| | - A V Lukoyanov
- Institute of Metal Physics, Russian Academy of Sciences, 620990 Yekaterinburg, Russia
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72
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Böhmer AE, Burger P, Hardy F, Wolf T, Schweiss P, Fromknecht R, Reinecker M, Schranz W, Meingast C. Nematic susceptibility of hole-doped and electron-doped BaFe2As2 iron-based superconductors from shear modulus measurements. PHYSICAL REVIEW LETTERS 2014; 112:047001. [PMID: 24580480 DOI: 10.1103/physrevlett.112.047001] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Indexed: 06/03/2023]
Abstract
The nematic susceptibility, χφ, of hole-doped Ba(1-x)K(x)Fe2As2 and electron-doped Ba(Fe(1-x)Co(x))2As2 iron-based superconductors is obtained from measurements of the elastic shear modulus using a three-point bending setup in a capacitance dilatometer. Nematic fluctuations, although weakened by doping, extend over the whole superconducting dome in both systems, suggesting their close tie to superconductivity. Evidence for quantum critical behavior of χφ is, surprisingly, only found for Ba(Fe(1-x)Co(x))2As2 and not for Ba(1-x)K(x)Fe2As2--the system with the higher maximal Tc value.
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Affiliation(s)
- A E Böhmer
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany and Fakultät für Physik, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - P Burger
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany and Fakultät für Physik, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - F Hardy
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - T Wolf
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - P Schweiss
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - R Fromknecht
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - M Reinecker
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna A-1090, Austria
| | - W Schranz
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna A-1090, Austria
| | - C Meingast
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
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73
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Laughlin RB. Fermi-liquid computation of the phase diagram of high-Tc cuprate superconductors with an orbital antiferromagnetic pseudogap. PHYSICAL REVIEW LETTERS 2014; 112:017004. [PMID: 24483922 DOI: 10.1103/physrevlett.112.017004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Indexed: 06/03/2023]
Abstract
A 4-parameter Fermi-liquid calculation of the high-Tc cuprate phase diagram is reported. Simultaneously accounted for are the special doping densities of 5% and 16%, the d-wave functional form of the (orbital antiferromagnetic) pseudogap, the measured Tc, superconducting gap, pseudogap and superfluid density as a function of doping, the particle-hole doping asymmetry and the half-filling spin wave velocity.
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Affiliation(s)
- R B Laughlin
- Department of Physics, Stanford University, Stanford, California 94305, USA
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74
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Concepts relating magnetic interactions, intertwined electronic orders, and strongly correlated superconductivity. Proc Natl Acad Sci U S A 2013; 110:17623-30. [PMID: 24114268 DOI: 10.1073/pnas.1316512110] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Unconventional superconductivity (SC) is said to occur when Cooper pair formation is dominated by repulsive electron-electron interactions, so that the symmetry of the pair wave function is other than an isotropic s-wave. The strong, on-site, repulsive electron-electron interactions that are the proximate cause of such SC are more typically drivers of commensurate magnetism. Indeed, it is the suppression of commensurate antiferromagnetism (AF) that usually allows this type of unconventional superconductivity to emerge. Importantly, however, intervening between these AF and SC phases, intertwined electronic ordered phases (IP) of an unexpected nature are frequently discovered. For this reason, it has been extremely difficult to distinguish the microscopic essence of the correlated superconductivity from the often spectacular phenomenology of the IPs. Here we introduce a model conceptual framework within which to understand the relationship between AF electron-electron interactions, IPs, and correlated SC. We demonstrate its effectiveness in simultaneously explaining the consequences of AF interactions for the copper-based, iron-based, and heavy-fermion superconductors, as well as for their quite distinct IPs.
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75
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Zapf S, Jeevan HS, Ivek T, Pfister F, Klingert F, Jiang S, Wu D, Gegenwart P, Kremer RK, Dressel M. EuFe2(As(1-x)P(x))2: reentrant spin glass and superconductivity. PHYSICAL REVIEW LETTERS 2013; 110:237002. [PMID: 25167524 DOI: 10.1103/physrevlett.110.237002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Indexed: 06/03/2023]
Abstract
By systematic investigations of the magnetic, transport, and thermodynamic properties of single crystals of EuFe(2)(As(1-x)P(x))(2) (0≤x≤1), we explore the complex interplay of superconductivity and Eu(2+) magnetism. Below 30 K, two magnetic transitions are observed for all P substituted crystals, suggesting a revision of the phase diagram. In addition to the canted A-type antiferromagnetic order of Eu(2+) at ∼20 K, a spin glass transition is discovered at lower temperatures. Most remarkably, the reentrant spin glass state of EuFe(2)(As(1-x)P(x))(2) coexists with superconductivity around x≈0.2.
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Affiliation(s)
- S Zapf
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - H S Jeevan
- I. Physikalisches Institut, Georg-August Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - T Ivek
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - F Pfister
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - F Klingert
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - S Jiang
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - D Wu
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - P Gegenwart
- I. Physikalisches Institut, Georg-August Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - R K Kremer
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - M Dressel
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
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76
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Levitin LV, Bennett RG, Casey A, Cowan B, Saunders J, Drung D, Schurig T, Parpia JM. Phase Diagram of the Topological Superfluid
3
He Confined in a Nanoscale Slab Geometry. Science 2013; 340:841-4. [DOI: 10.1126/science.1233621] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- L. V. Levitin
- Department of Physics, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
| | - R. G. Bennett
- Department of Physics, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
| | - A. Casey
- Department of Physics, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
| | - B. Cowan
- Department of Physics, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
| | - J. Saunders
- Department of Physics, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
| | - D. Drung
- Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, D-10587 Berlin, Germany
| | - Th. Schurig
- Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, D-10587 Berlin, Germany
| | - J. M. Parpia
- Department of Physics, Cornell University, Ithaca, NY 14853, USA
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77
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Moon SJ, Schafgans AA, Tanatar MA, Prozorov R, Thaler A, Canfield PC, Sefat AS, Mandrus D, Basov DN. Interlayer coherence and superconducting condensate in the c-axis response of optimally doped Ba(Fe(1-x)Co(x))2As2 high-T(c) superconductor using infrared spectroscopy. PHYSICAL REVIEW LETTERS 2013; 110:097003. [PMID: 23496739 DOI: 10.1103/physrevlett.110.097003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Indexed: 06/01/2023]
Abstract
We report on the infrared studies of the interlayer charge dynamics of a prototypical pnictide superconductor Ba(Fe(0.926)Co(0.074))(2)As(2). We succeeded in probing the intrinsic interlayer response by performing infrared experiments on the crystals with a cleaved ac surface. Our experiments identify the coexistence of the suppression of the electronic spectral weight and the development of a coherent Drude-like response in the normal state. The formation of the interlayer condensate is clearly observed in the superconducting state and appears to be linked to coherent contribution to the normal-state conductivity.
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Affiliation(s)
- S J Moon
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
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78
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Matsubayashi K, Tanaka T, Sakai A, Nakatsuji S, Kubo Y, Uwatoko Y. Pressure-induced heavy fermion superconductivity in the nonmagnetic quadrupolar system PrTi(2)Al(20). PHYSICAL REVIEW LETTERS 2012; 109:187004. [PMID: 23215319 DOI: 10.1103/physrevlett.109.187004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Indexed: 06/01/2023]
Abstract
We report the discovery of a pressure-induced heavy fermion superconductivity in a nonmagnetic orbital ordering state in the cubic compound PrTi(2)Al(20). In particular, we found that the transition temperature and the effective mass associated with the superconductivity are dramatically enhanced as the system approaches the putative quantum critical point of the orbital order. Our experiment indicates that the strong orbital fluctuations may provide a nonmagnetic glue for Cooper pairing.
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Affiliation(s)
- K Matsubayashi
- Institute for Solid State Physics, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
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79
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Doan P, Gooch M, Tang Z, Lorenz B, Möller A, Tapp J, Chu PCW, Guloy AM. Ba1–xNaxTi2Sb2O (0.0 ≤ x ≤ 0.33): A Layered Titanium-Based Pnictide Oxide Superconductor. J Am Chem Soc 2012; 134:16520-3. [DOI: 10.1021/ja3078889] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | | | | | | | - Paul C. W. Chu
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California
94720, United States
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80
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Ruff JPC, Chu JH, Kuo HH, Das RK, Nojiri H, Fisher IR, Islam Z. Susceptibility anisotropy in an iron arsenide superconductor revealed by x-ray diffraction in pulsed magnetic fields. PHYSICAL REVIEW LETTERS 2012; 109:027004. [PMID: 23030198 DOI: 10.1103/physrevlett.109.027004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Indexed: 06/01/2023]
Abstract
In addition to unconventional high-T(c) superconductivity, the iron arsenides exhibit strong magnetoelastic coupling and a notable electronic anisotropy within the a-b plane. We relate these properties by studying underdoped Ba(Fe(1-x)Co(x))2As2 by x-ray diffraction in pulsed magnetic fields up to 27.5 T. We exploit magnetic detwinning effects to demonstrate anisotropy in the in-plane susceptibility, which develops at the structural phase transition despite the absence of magnetic order. The degree of detwinning increases smoothly with decreasing temperature, and a single-domain condition is realized over a range of field and temperature. At low temperatures we observe an activated behavior, with a large hysteretic remnant effect. Detwinning was not observed within the superconducting phase for accessible magnetic fields.
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Affiliation(s)
- J P C Ruff
- The Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
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81
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Bauer M, Parish MM. Dipolar gases in coupled one-dimensional lattices. PHYSICAL REVIEW LETTERS 2012; 108:255302. [PMID: 23004615 DOI: 10.1103/physrevlett.108.255302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Indexed: 06/01/2023]
Abstract
We consider dipolar bosons in two tubes of one-dimensional lattices, where the dipoles are aligned to be maximally repulsive and the particle filling fraction is the same in each tube. In the classical limit of zero intersite hopping, the particles arrange themselves into an ordered crystal for any rational filling fraction, forming a complete devil's staircase like in the single tube case. Turning on hopping within each tube then gives rise to a competition between the crystalline Mott phases and a liquid of defects or solitons. However, for the two-tube case, we find that solitons from different tubes can bind into pairs for certain topologies of the filling fraction. This provides an intriguing example of pairing that is purely driven by correlations close to a Mott insulator.
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Affiliation(s)
- Marianne Bauer
- Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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82
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Mailman A, Winter SM, Yu X, Robertson CM, Yong W, Tse JS, Secco RA, Liu Z, Dube PA, Howard JAK, Oakley RT. Crossing the Insulator-to-Metal Barrier with a Thiazyl Radical Conductor. J Am Chem Soc 2012; 134:9886-9. [DOI: 10.1021/ja303169y] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Aaron Mailman
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Stephen M. Winter
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Xin Yu
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | | | - Wenjun Yong
- Department
of Earth Sciences, University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - John S. Tse
- Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Richard A. Secco
- Department
of Earth Sciences, University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Zhenxian Liu
- Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch
Road NW, Washington, D.C. 20015, United States
| | - Paul A. Dube
- Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | | | - Richard T. Oakley
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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83
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Kim KW, Pashkin A, Schäfer H, Beyer M, Porer M, Wolf T, Bernhard C, Demsar J, Huber R, Leitenstorfer A. Ultrafast transient generation of spin-density-wave order in the normal state of BaFe2As2 driven by coherent lattice vibrations. NATURE MATERIALS 2012; 11:497-501. [PMID: 22484832 DOI: 10.1038/nmat3294] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 03/05/2012] [Indexed: 05/31/2023]
Abstract
The interplay among charge, spin and lattice degrees of freedom in solids gives rise to intriguing macroscopic quantum phenomena such as colossal magnetoresistance, multiferroicity and high-temperature superconductivity. Strong coupling or competition between various orders in these systems presents the key to manipulate their functional properties by means of external perturbations such as electric and magnetic fields or pressure. Ultrashort and intense optical pulses have emerged as an interesting tool to investigate elementary dynamics and control material properties by melting an existing order. Here, we employ few-cycle multi-terahertz pulses to resonantly probe the evolution of the spin-density-wave (SDW) gap of the pnictide compound BaFe(2)As(2) following excitation with a femtosecond optical pulse. When starting in the low-temperature ground state, optical excitation results in a melting of the SDW order, followed by ultrafast recovery. In contrast, the SDW gap is induced when we excite the normal state above the transition temperature. Very surprisingly, the transient ordering quasi-adiabatically follows a coherent lattice oscillation at a frequency as high as 5.5 THz. Our results attest to a pronounced spin-phonon coupling in pnictides that supports rapid development of a macroscopic order on small vibrational displacement even without breaking the symmetry of the crystal.
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84
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Kallin C. Chiral p-wave order in Sr2RuO4. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2012; 75:042501. [PMID: 22790504 DOI: 10.1088/0034-4885/75/4/042501] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Shortly after the discovery in 1994 of superconductivity in Sr(2)RuO(4), it was proposed on theoretical grounds that the superconducting state may have chiral p-wave symmetry analogous to the A phase of superfluid (3)He. Substantial experimental evidence has since accumulated in favor of this pairing symmetry, including several interesting recent results related to broken time-reversal symmetry (BTRS) and vortices with half of the usual superconducting flux quantum. Great interest surrounds the possibility of chiral p-wave order in Sr(2)RuO(4), since this state may exhibit topological order analogous to that of a quantum Hall state, and can support such exotic physics as Majorana fermions and non-Abelian winding statistics, which have been proposed as one route to a quantum computer. However, serious discrepancies remain in trying to connect the experimental results to theoretical predictions for chiral p-wave order. In this paper, I review a broad range of experiments on Sr(2)RuO(4) that are sensitive to p-wave pairing, triplet superconductivity and time-reversal symmetry breaking and compare these experiments to each other and to theoretical predictions. In this context, the evidence for triplet pairing is strong, although some puzzles remain. The 'smoking gun' experimental results for chiral p-wave order, those which directly look for evidence of BTRS in the superconducting state of Sr(2)RuO(4), are most perplexing when the results are compared with each other and to theoretical predictions. Consequently, the case for chiral p-wave superconductivity in Sr(2)RuO(4) remains unresolved, suggesting the need to consider either significant modifications to the standard chiral p-wave models or possible alternative pairing symmetries. Recent ideas along these lines are discussed.
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Affiliation(s)
- Catherine Kallin
- Department of Physics and Astronomy, McMaster University, Hamilton ON L8S 4M1, Canada.
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85
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Hu T, Xiao H, Sayles TA, Dzero M, Maple MB, Almasan CC. Strong magnetic fluctuations in a superconducting state of CeCoIn5. PHYSICAL REVIEW LETTERS 2012; 108:056401. [PMID: 22400944 DOI: 10.1103/physrevlett.108.056401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2011] [Indexed: 05/31/2023]
Abstract
We show results on the vortex core dissipation through current-voltage measurements under applied pressure and magnetic field in the superconducting phase of CeCoIn{5}. We find that as soon as the system becomes superconducting, the vortex core resistivity increases sharply as the temperature and magnetic field decrease. The sharp increase in flux-flow resistivity is due to quasiparticle scattering on critical antiferromagnetic fluctuations. The strength of magnetic fluctuations below the superconducting transition suggests that magnetism is complementary to superconductivity and therefore must be considered in order to fully account for the low-temperature properties of CeCoIn{5}.
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Affiliation(s)
- T Hu
- Department of Physics, Kent State University, Kent, Ohio 44242, USA
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86
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d-Wave Superconductivity and s-Wave Charge Density Waves: Coexistence between Order Parameters of Different Origin and Symmetry. Symmetry (Basel) 2011. [DOI: 10.3390/sym3040699] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
A review of the theory describing the coexistence between d-wave superconductivity and s-wave charge-density-waves (CDWs) is presented. The CDW gapping is identified with pseudogapping observed in high-Tc oxides. According to the cuprate specificity, the analysis is carried out for the two-dimensional geometry of the Fermi surface (FS). Phase diagrams on the σ0 − α plane—here, σ0 is the ratio between the energy gaps in the parent pure CDW and superconducting states, and the quantity 2α is connected with the degree of dielectric (CDW) FS gapping—were obtained for various possible configurations of the order parameters in the momentum space. Relevant tunnel and photoemission experimental data for high-Tc oxides are compared with theoretical predictions. A brief review of the results obtained earlier for the coexistence between s-wave superconductivity and CDWs is also given.
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87
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Transition behavior on lattices with ladders. Part II: Sensitivity to coupling. Chem Phys Lett 2011. [DOI: 10.1016/j.cplett.2011.08.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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88
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Jin K, Butch NP, Kirshenbaum K, Paglione J, Greene RL. Link between spin fluctuations and electron pairing in copper oxide superconductors. Nature 2011; 476:73-5. [DOI: 10.1038/nature10308] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 06/15/2011] [Indexed: 11/09/2022]
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