1
|
Thareja E, MacPeak K, Sprunger PT, Vekhter I, Shelton WA. Trends in hot carrier distribution for disordered noble-transition metal alloys. J Phys Condens Matter 2024. [PMID: 38714190 DOI: 10.1088/1361-648x/ad4840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2024]
Abstract
We have developed an approach for predicting trends for efficient hot carrier generation among disordered metal alloys. We provide a simple argument for the importance of indirect transitions in the presence of disorder, thus justifying the use of Joint Density of States (JDOS)-like quantities for exploring these trends. We introduce a new JDOS-like quantity, JDOSK, which heuristically incorporates differences in particle lifetimes depending on their excitation energies. To demonstrate the efficacy of this new quantity, we apply it to the study of Cu50X50 where X = Ag, Au, Pd and Y50Pd50 where Y = Au, Ni. We predict that Ni50Pd50 produces the most hot carriers among the alloys considered. The improvement in the density of excited photocarriers over the base alloy used, Cu50Ag50, is 3.4 times for 800 nm and 19 times for 1550 nm light. This boost in hot-carrier generation is consequence of the ferromagnetic nature of the Ni alloy. We argue that our method allows efficient material-specific predictions for low bias photoconductivity of alloys.
Collapse
Affiliation(s)
- Eklavya Thareja
- Louisiana State University, Department of Physics and Astronomy, Baton Rouge, Louisiana, 70803-2804, UNITED STATES
| | - Kevin MacPeak
- Louisiana State University, Cain Department of Chemical Engineering, Baton Rouge, Louisiana, 70803-2804, UNITED STATES
| | - Phillip T Sprunger
- Louisiana State University, Department of Physics and Astronomy, Baton Rouge, Louisiana, 70803-2804, UNITED STATES
| | - Ilya Vekhter
- Louisiana State University, Department of Physics and Astronomy, Baton Rouge, Louisiana, 70803-2804, UNITED STATES
| | - William A Shelton
- Louisiana State University, Department of Physics and Astronomy, Baton Rouge, Louisiana, 70803-2804, UNITED STATES
| |
Collapse
|
2
|
Matsushita T, Ando J, Masaki Y, Mizushima T, Fujimoto S, Vekhter I. Spin-Nernst Effect in Time-Reversal-Invariant Topological Superconductors. Phys Rev Lett 2022; 128:097001. [PMID: 35302805 DOI: 10.1103/physrevlett.128.097001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 02/05/2022] [Indexed: 06/14/2023]
Abstract
We investigate the spin-Nernst effect in time-reversal-invariant topological superconductors, and show that it provides smoking-gun evidence for helical Cooper pairs. The spin-Nernst effect stems from asymmetric, in spin space, scattering of quasiparticles at nonmagnetic impurities, and generates a transverse spin current by the temperature gradient. Both the sign and the magnitude of the effect sensitively depend on the scattering phase shift at impurity sites. Therefore the spin-Nernst effect is uniquely suitable for identifying time-reversal-invariant topological superconducting orders.
Collapse
Affiliation(s)
- Taiki Matsushita
- Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Jiei Ando
- Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Yusuke Masaki
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Takeshi Mizushima
- Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Satoshi Fujimoto
- Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
- Center for Quantum Information and Quantum Biology, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Ilya Vekhter
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803-4001, USA
| |
Collapse
|
3
|
Karna SK, Marshall M, Xie W, DeBeer-Schmitt L, Young DP, Vekhter I, Shelton WA, Kovács A, Charilaou M, DiTusa JF. Annihilation and Control of Chiral Domain Walls with Magnetic Fields. Nano Lett 2021; 21:1205-1212. [PMID: 33492966 PMCID: PMC7883385 DOI: 10.1021/acs.nanolett.0c03199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 01/17/2021] [Indexed: 06/12/2023]
Abstract
The control of domain walls is central to nearly all magnetic technologies, particularly for information storage and spintronics. Creative attempts to increase storage density need to overcome volatility due to thermal fluctuations of nanoscopic domains and heating limitations. Topological defects, such as solitons, skyrmions, and merons, may be much less susceptible to fluctuations, owing to topological constraints, while also being controllable with low current densities. Here, we present the first evidence for soliton/soliton and soliton/antisoliton domain walls in the hexagonal chiral magnet Mn1/3NbS2 that respond asymmetrically to magnetic fields and exhibit pair-annihilation. This is important because it suggests the possibility of controlling the occurrence of soliton pairs and the use of small fields or small currents to control nanoscopic magnetic domains. Specifically, our data suggest that either soliton/soliton or soliton/antisoliton pairs can be stabilized by tuning the balance between intrinsic exchange interactions and long-range magnetostatics in restricted geometries.
Collapse
Affiliation(s)
- Sunil K. Karna
- Department
of Physics and Astronomy, Louisiana State
University, Baton
Rouge, Louisiana 70803, United States
- Department
of Physics and Center for Materials Research, Norfolk State University, Norfolk, Virginia 23504, United States
| | - Madalynn Marshall
- Department
of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Weiwei Xie
- Department
of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Lisa DeBeer-Schmitt
- Neutron
Scattering Division, Oak Ridge National
Laboratory, Oak Ridge, Tennessee 37831, United States
| | - David P. Young
- Department
of Physics and Astronomy, Louisiana State
University, Baton
Rouge, Louisiana 70803, United States
| | - Ilya Vekhter
- Department
of Physics and Astronomy, Louisiana State
University, Baton
Rouge, Louisiana 70803, United States
| | - William A. Shelton
- Cain
Department of Chemical Engineering, Louisiana
State University, Baton
Rouge, Louisiana 70803, United States
| | - Andras Kovács
- Ernst Ruska-Centre
for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Michalis Charilaou
- Department
of Physics, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
| | - John F. DiTusa
- Department
of Physics and Astronomy, Louisiana State
University, Baton
Rouge, Louisiana 70803, United States
- Department
of Physics, Indiana University-Purdue University
Indianapolis, Indianapolis, Indiana 46202, United States
| |
Collapse
|
4
|
Shirali K, Shelton WA, Vekhter I. Importance of van der Waals interactions for ab initiostudies of topological insulators. J Phys Condens Matter 2020; 33:035702. [PMID: 33007759 DOI: 10.1088/1361-648x/abbdbc] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 10/02/2020] [Indexed: 06/11/2023]
Abstract
We investigate the lattice and electronic structures of the bulk and surface of the prototypical layered topological insulators Bi2Se3and Bi2Te3usingab initiodensity functional methods, and systematically compare the results of different methods of including van der Waals (vdW) interactions. We show that the methods utilizing semi-empirical energy corrections yield accurate descriptions of these materials, with the most precise results obtained by properly accounting for the long-range tail of the vdW interactions. The bulk lattice constants, distances between quintuple layers and the Dirac velocity of the topological surface states (TSS) are all in excellent agreement with experiment. In Bi2Te3, hexagonal warping of the energy dispersion leads to complex spin textures of the TSS at moderate energies, while in Bi2Se3these states remain almost perfectly helical away from the Dirac point, showing appreciable signs of hexagonal warping at much higher energies, above the minimum of the bulk conduction band. Our results establish a framework for unified and systematic self-consistent first principles calculations of topological insulators in bulk, slab and interface geometries, and provides the necessary first step towardab initiomodeling of topological heterostructures.
Collapse
Affiliation(s)
- K Shirali
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001, United States of America
| | - W A Shelton
- Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803-4001, United States of America
- Center for Computation and Technology, Louisiana State University, Baton Rouge, LA 70803-4001, United States of America
| | - I Vekhter
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001, United States of America
| |
Collapse
|
5
|
Baireuther P, Orth PP, Vekhter I, Schmalian J. Manipulation of a two-photon pump in superconductor-semiconductor heterostructures. Phys Rev Lett 2014; 112:077003. [PMID: 24579628 DOI: 10.1103/physrevlett.112.077003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Indexed: 06/03/2023]
Abstract
We investigate the photon statistics, entanglement, and squeezing of a p-n junction sandwiched between two superconducting leads and show that such an electrically driven photon pump generates correlated and entangled pairs of photons. In particular, we demonstrate that the squeezing of the fluctuations in the quadrature amplitudes of the emitted light can be manipulated by changing the relative phase of the order parameters of the superconductors. This reveals how macroscopic coherence of the superconducting state can be used to tailor the properties of a two-photon state.
Collapse
Affiliation(s)
- Paul Baireuther
- Institute for Theory of Condensed Matter, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany and Instituut-Lorentz, Universiteit Leiden, Post Office Box 9506, 2300 RA Leiden, The Netherlands
| | - Peter P Orth
- Institute for Theory of Condensed Matter, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | - Ilya Vekhter
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | - Jörg Schmalian
- Institute for Theory of Condensed Matter, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| |
Collapse
|
6
|
Isaev L, Aoyama K, Paul I, Vekhter I. Orbital order and Hund's rule frustration in Kondo lattices. Phys Rev Lett 2013; 111:157202. [PMID: 24160623 DOI: 10.1103/physrevlett.111.157202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Indexed: 06/02/2023]
Abstract
We analyze a microscopic origin of the Kondo effect-assisted orbital order in heavy-fermion materials. By studying the periodic two-orbital Anderson model with two local electrons, we show that frustration of Hund's rule coupling due to the Kondo effect leads to an incommensurate spiral orbital and magnetic order, which exists only inside the Kondo screened (heavy-electron) phase. This spiral state can be observed in neutron and resonant x-ray scattering measurements in U- and Pr-based heavy-fermion compounds, and realized in cold atomic gases, e.g., fermionic 173Yb.
Collapse
Affiliation(s)
- L Isaev
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 80703, USA
| | | | | | | |
Collapse
|
7
|
Romano A, Gentile P, Noce C, Vekhter I, Cuoco M. Magnetic intragap states and mixed parity pairing at the edge of spin-triplet superconductors. Phys Rev Lett 2013; 110:267002. [PMID: 23848911 DOI: 10.1103/physrevlett.110.267002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 02/05/2013] [Indexed: 06/02/2023]
Abstract
We show that a spontaneous magnetic moment may appear at the edge of a spin-triplet superconductor if the system allows for pairing in a subdominant channel. To unveil the microscopic mechanism behind such an effect, we combine numerical solution of the Bogoliubov-de Gennes equations for a tight-binding model with nearest-neighbor attraction, and the symmetry based Ginzburg-Landau approach. We find that a potential barrier modulating the electronic density near the edge of the system leads to a nonunitary superconducting state close to the boundary where spin-singlet pairing coexists with the dominant triplet superconducting order. We demonstrate that the spin polarization at the edge appears due to the inhomogeneity of the nonunitary state and originates in the lifting of the spin degeneracy of the Andreev bound states.
Collapse
Affiliation(s)
- Alfonso Romano
- CNR-SPIN, I-84084 Fisciano (Salerno), Italy and Dipartimento di Fisica E. R. Caianiello, Università di Salerno, I-84084 Fisciano (Salerno), Italy
| | | | | | | | | |
Collapse
|
8
|
Aoyama K, Beaird R, Sheehy DE, Vekhter I. Inhomogeneous superconducting States of mesoscopic thin-walled cylinders in external magnetic fields. Phys Rev Lett 2013; 110:177004. [PMID: 23679762 DOI: 10.1103/physrevlett.110.177004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Indexed: 06/02/2023]
Abstract
We theoretically investigate the appearance of spatially modulated superconducting states in mesoscopic superconducting thin-wall cylinders in a magnetic field at low temperatures. Quantization of the electron motion around the circumference of the cylinder leads to a discontinuous evolution of the spatial modulation of the superconducting order parameter along the transition line T(c)(H). We show that this discontinuity leads to the nonmonotonic behavior of the specific heat jump at the onset of superconductivity as a function of temperature and field. We argue that this geometry provides an excellent opportunity to directly and unambiguously detect distinctive signatures of the Fulde-Ferrell-Larkin-Ovchinnikov modulation of the superconducting order.
Collapse
Affiliation(s)
- K Aoyama
- The Hakubi Center for Advanced Research, Kyoto University, Kyoto 606-8501, Japan
| | | | | | | |
Collapse
|
9
|
Isaev L, Vekhter I. Heavy antiferromagnetic phases in Kondo lattices. Phys Rev Lett 2013; 110:026403. [PMID: 23383925 DOI: 10.1103/physrevlett.110.026403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Indexed: 06/01/2023]
Abstract
We propose a microscopic physical mechanism that stabilizes the coexistence of the Kondo effect and antiferromagnetism in heavy-fermion systems. We consider a two-dimensional quantum Kondo-Heisenberg lattice model and show that long-range electron hopping leads to a robust antiferromagnetic Kondo state. By using a modified slave-boson mean-field approach we analyze the stability of the heavy antiferromagnetic phase across a range of parameters, and discuss transitions between different phases. Our results may be used to guide future experiments on heavy fermion compounds.
Collapse
Affiliation(s)
- L Isaev
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 80703, USA
| | | |
Collapse
|
10
|
Das T, Vorontsov AB, Vekhter I, Graf MJ. Role of the Fermi-surface anisotropy in angle-dependent magnetic-field oscillations for identifying the energy-gap anisotropy of A(y)Fe(2)Se(2) superconductors. Phys Rev Lett 2012; 109:187006. [PMID: 23215321 DOI: 10.1103/physrevlett.109.187006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Indexed: 06/01/2023]
Abstract
We present a numerical study of the field-angle resolved oscillations of the thermal conductivity and specific heat under a rotated magnetic field in the A(y)Fe(2-x)Se(2) [A = K, Rb, Cs, (Tl, K)] superconductors, using realistic two-band Fermi surface parametrization. Our key finding is that even for isotropic pairing on an anisotropic Fermi surface, the thermodynamic quantities exhibit substantial oscillatory behavior in the superconducting state, even much below the upper critical field. Furthermore, in multiband systems the competition of anisotropies between two Fermi surfaces can cause a double sign reversal of oscillations as a function of temperature, irrespective of gap anisotropy. Our findings put severe constraints on simple interpretations of field-angle resolved measurements widely used to identify the angular structure of the superconducting gap.
Collapse
Affiliation(s)
- Tanmoy Das
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | | | | | | |
Collapse
|
11
|
Kato Y, Batista CD, Vekhter I. Antiferromagnetic order in Pauli-limited unconventional superconductors. Phys Rev Lett 2011; 107:096401. [PMID: 21929256 DOI: 10.1103/physrevlett.107.096401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Indexed: 05/31/2023]
Abstract
We develop a theory of the coexistence of superconductivity (SC) and antiferromagnetism (AFM) in CeCoIn(5). We show that in Pauli-limited nodal superconductors the nesting of the quasiparticle pockets induced by Zeeman pair breaking leads to incommensurate AFM with the magnetic moment normal to the field. We compute the phase diagram and find a first order transition to the normal state at low temperatures, the absence of normal state AFM, and the coexistence of SC and AFM at high fields, in agreement with experiments. We also predict the existence of a new double-Q magnetic phase.
Collapse
Affiliation(s)
- Yasuyuki Kato
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | | | | |
Collapse
|
12
|
Vorontsov AB, Vekhter I. Nodes versus minima in the energy gap of iron pnictide superconductors from field-induced anisotropy. Phys Rev Lett 2010; 105:187004. [PMID: 21231129 DOI: 10.1103/physrevlett.105.187004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Indexed: 05/30/2023]
Abstract
We develop the formalism for computing the oscillations of the specific heat and thermal transport under rotated magnetic field in multiband superconductors with anisotropic gap and apply it to iron-based materials. We show that these oscillations change sign at low temperatures and fields, which strongly influences the experimental conclusions about the gap structure. We find that recent measurements of the specific heat oscillations indicate that the iron-based superconductors possess an anisotropic gap with deep minima or nodes close to the line connecting electron and hole pockets. We predict the behavior of the thermal conductivity that will help distinguish between these cases.
Collapse
Affiliation(s)
- A B Vorontsov
- Department of Physics, Montana State University, Bozeman, Montana 59717, USA
| | | |
Collapse
|
13
|
Vorontsov AB, Vekhter I, Eschrig M. Surface bound states and spin currents in noncentrosymmetric superconductors. Phys Rev Lett 2008; 101:127003. [PMID: 18851405 DOI: 10.1103/physrevlett.101.127003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Indexed: 05/26/2023]
Abstract
We investigate the ground state properties of a noncentrosymmetric superconductor near a surface. We determine the spectrum of Andreev bound states due to surface-induced mixing of bands with opposite spin helicities for a Rashba-type spin-orbit coupling. We find that the order parameter suppression qualitatively changes the bound state spectrum. The spin structure of Andreev states leads to a spin supercurrent along the interface, which is strongly enhanced compared to the normal state spin current. Particle and hole coherence amplitudes show Faraday-like rotations of the spin along quasiparticle trajectories.
Collapse
Affiliation(s)
- A B Vorontsov
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
| | | | | |
Collapse
|
14
|
Kasahara Y, Iwasawa T, Shimizu Y, Shishido H, Shibauchi T, Vekhter I, Matsuda Y. Thermal conductivity evidence for a dx2-y2 pairing symmetry in the heavy-fermion CeIrIn5 superconductor. Phys Rev Lett 2008; 100:207003. [PMID: 18518572 DOI: 10.1103/physrevlett.100.207003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Indexed: 05/26/2023]
Abstract
The phase diagram of the quasi-2D Ce(Ir,Rh)In5 system contains two distinct superconducting domes. By the thermal transport measurements in rotating magnetic fields H, we pinned down the superconducting gap structure of CeIrIn5 in the second dome, located distant from the first dome in proximity to an antiferromagnetic quantum critical point. Clear fourfold oscillation was observed when H is rotated within the ab plane, while no oscillation was observed within the bc plane. In sharp contrast to previous reports, our results are most consistent with dx2-y2 symmetry, implying that the superconductivity in the second phase is also mediated by antiferromagnetic spin fluctuations.
Collapse
Affiliation(s)
- Y Kasahara
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | | | | | | | | | | | | |
Collapse
|
15
|
Vorontsov A, Vekhter I. Nodal structure of quasi-two-dimensional superconductors probed by a magnetic field. Phys Rev Lett 2006; 96:237001. [PMID: 16803392 DOI: 10.1103/physrevlett.96.237001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2006] [Indexed: 05/10/2023]
Abstract
We consider a quasi-two-dimensional superconductor with line nodes in the presence of an in-plane magnetic field, and compute the dependence of the specific heat C and the in-plane heat conductivity kappa on the angle between the field and the nodal direction in the vortex state. We use a variation of the microscopic Brandt-Pesch-Tewordt method that accounts for the scattering of quasiparticles off vortices, and analyze the signature of the nodes in C and kappa. At low to moderate fields the specific heat anisotropy changes sign with increasing temperature. Comparison with measurements of C and kappa in CeCoIn(5) resolves the contradiction between the two in favor of the d((x(2)-y(2)) gap.
Collapse
Affiliation(s)
- A Vorontsov
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | | |
Collapse
|
16
|
Harrison N, Alver U, Goodrich RG, Vekhter I, Sarrao JL, Pagliuso PG, Moreno NO, Balicas L, Fisk Z, Hall D, Macaluso RT, Chan JY. 4f-electron localization in CexLa 1-xM In5 with M=Co, Rh, or Ir. Phys Rev Lett 2004; 93:186405. [PMID: 15525189 DOI: 10.1103/physrevlett.93.186405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2004] [Indexed: 05/24/2023]
Abstract
de Haas-van Alphen measurements on Ce(x)La(1-x)MIn(5) yield contrasting types of behavior that depend on whether M=Co and Ir or M=Rh. A stronger x-dependent scattering in the case of M=Co and Ir is suggestive of a stronger relative coupling, J/W, of the conduction electrons to the 4f electrons, which would then account for the development of a heavy composite Fermi-liquid state as x-->1. The failure of a composite Fermi-liquid state to form for any x in the case of M= Rh is shown to be inconsistent with theoretical models that propose antiferromagnetism to result from spin-density-wave formation.
Collapse
Affiliation(s)
- N Harrison
- National High Magnetic Field Laboratory, LANL, MS-E536, Los Alamos, New Mexico 87545, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Park T, Chia EEM, Salamon MB, Bauer ED, Vekhter I, Thompson JD, Choi EM, Kim HJ, Lee SI, Canfield PC. Evidence for the coexistence of an anisotropic superconducting gap and nonlocal effects in the nonmagnetic superconductor LuNi2B2C. Phys Rev Lett 2004; 92:237002. [PMID: 15245188 DOI: 10.1103/physrevlett.92.237002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2003] [Indexed: 05/24/2023]
Abstract
A study of the dependence of the heat capacity C(p)(alpha) on the field angle in LuNi2B2C reveals an anomalous disorder effect. For pure samples, C(p)(alpha) exhibits a fourfold variation as the field H<H(c2) is rotated in the [001] plane, with minima along <100> (alpha=0). A slightly disordered sample, however, develops anomalous secondary minima along <110> for mu(0)H>1 T, leading to an eightfold pattern at 2 K and 1.5 T. The anomalous pattern is discussed in terms of coexisting superconducting gap anisotropy and nonlocal effects.
Collapse
Affiliation(s)
- Tuson Park
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Bianchi A, Movshovich R, Vekhter I, Pagliuso PG, Sarrao JL. Avoided antiferromagnetic order and quantum critical point in CeCoIn5. Phys Rev Lett 2003; 91:257001. [PMID: 14754138 DOI: 10.1103/physrevlett.91.257001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2003] [Indexed: 05/24/2023]
Abstract
We measured the specific heat and resistivity of heavy fermion CeCoIn5 between the superconducting critical field H(c2)=5 T and 9 T, with the field in the [001] direction, and at temperatures down to 50 mK. At 5 T the data show a non-Fermi liquid (NFL) behavior down to the lowest temperatures. At the field above 8 T the data exhibit a crossover from the Fermi liquid to a non-Fermi liquid behavior. We analyzed the scaling properties of the specific heat and compared both the resistivity and the specific heat with the predictions of a spin-fluctuation theory. Our analysis leads us to suggest that the NFL behavior is due to incipient antiferromagnetism (AFM) in CeCoIn5 with the quantum critical point in the vicinity of H(c2). Below H(c2) the AFM phase which competes with the paramagnetic ground state is superseded by the superconducting transition.
Collapse
Affiliation(s)
- A Bianchi
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | | | | | | | | |
Collapse
|
19
|
Vekhter I, Varma CM. Proposal to determine the spectrum of pairing glue in high-temperature superconductors. Phys Rev Lett 2003; 90:237003. [PMID: 12857282 DOI: 10.1103/physrevlett.90.237003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2002] [Indexed: 05/24/2023]
Abstract
We propose a method for an analysis of the angle-resolved photoemission data in two-dimensional anisotropic superconductors which directly yields the spectral function of the bosons mediating Cooper pairing. The method includes a self-consistency check for the validity of the approximations made in the analysis. We explicitly describe the experimental data needed for implementing the proposed procedure.
Collapse
Affiliation(s)
- I Vekhter
- Theoretical Division, MS B262, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | | |
Collapse
|
20
|
Shytov AV, Vekhter I, Gruzberg IA, Balatsky AV. Tail states in clean superconductors with magnetic impurities. Phys Rev Lett 2003; 90:147002. [PMID: 12731939 DOI: 10.1103/physrevlett.90.147002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2002] [Indexed: 05/24/2023]
Abstract
We analyze the behavior of the density of states in a singlet s-wave superconductor with weak magnetic impurities in the clean limit. By using the method of optimal fluctuation and treating the order parameter self-consistently we show that the density of states is finite everywhere in the superconducting gap, and that it varies as ln(N(E) proportional to -/E-Delta(0)/((7-d)/4) near the mean field gap edge Delta(0) in a d-dimensional superconductor. In contrast to most studied cases the optimal fluctuation is strongly anisotropic.
Collapse
Affiliation(s)
- A V Shytov
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106, USA
| | | | | | | |
Collapse
|
21
|
Vekhter I, Bulaevskii LN, Koshelev AE, Maley MP. Interlayer quasiparticle transport in the vortex state of josephson coupled superconductors. Phys Rev Lett 2000; 84:1296-1299. [PMID: 11017502 DOI: 10.1103/physrevlett.84.1296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/1999] [Indexed: 05/23/2023]
Abstract
We calculate the dependence of the interlayer quasiparticle conductivity, sigma(q), in a Josephson coupled d-wave superconductor on the magnetic field B parallelc and the temperature T. We consider a clean superconductor with resonant impurity scattering and a dominant coherent interlayer tunneling. When pancake vortices in adjacent layers are weakly correlated, at low T the conductivity increases sharply with B over a field scale determined by the impurity scattering, before reaching an extended region of slow linear growth. At high T the conductivity initially decreases and then reaches the same linear regime. For correlated pancakes, sigma(q) increases much more strongly with the applied field.
Collapse
Affiliation(s)
- I Vekhter
- Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | | | | | | |
Collapse
|