Specific heat, magnetic susceptibility, resistivity and thermal expansion of the superconductor ZrB12

  title={Specific heat, magnetic susceptibility, resistivity and thermal expansion of the superconductor ZrB12},
  author={Rolf Lortz and Yi Wang and Satoko Abe and Christoph Meingast and Yu. B. Paderno and Vladimir B. Filippov and Alain F. Junod},
  journal={Physical Review B},
In an attempt to clarify conflicting published data, we report new measurements of specific heat, resistivity, magnetic susceptibility, and thermal expansivity up to room temperature for the 6 K superconductor ZrB12, using well-characterized single crystals with a residual resistivity ratio 9. The specific heat gives the bulk result 20/ kBTc=3.7 for the superconducting gap ratio, and excludes multiple gaps and d-wave symmetry for the Cooper pairs. The Sommerfeld constant n=0.34 mJ K 2 gat 1… Expand
Electron transport and superconducting properties of ZrB12 and YB6
Abstract We report the measurements of the temperature dependence of the resistivity, ρ ( T ), magnetic penetration depth, λ ( T ), the lower, H c 1 ( T ), and upper, H c 2 ( T ), critical magneticExpand
Electron Structure, Transport, and Superconducting Properties of ZrB 12 , ZrB 2 , YB 6 and MgB 2
We report the review of the measurements of the temperature dependence of the resistivity, ρ(T), magnetic penetration depth, λ(T), the lower, Hc1(T), and upper, Hc2(T), critical magnetic fields, forExpand
Optical study of electronic structure and electron-phonon coupling in ZrB12
We report the optical 6 meV–4 eV properties of a boride superconductor ZrB12 Tc=6 K in the normal state from 20 to 300 K measured on high-quality single crystals by a combination of reflectivity andExpand
Isotope effect in charge transport of LuB12
The galvanomagnetic properties of single-crystal samples with various isotopic boron compositions have been investigated for the first time for the normal state of superconductor LuB12 (Tc ≈ 0.44 K).Expand
10B–11B isotope substitution and superconductivity in ZrB12
The specific heat of the ZrB12 compound in the normal and superconducting states (TC ≈ 6 K) has been studied in the 1.9–7 K temperature range for high-quality single crystals with different relativeExpand
Phonon density of states, anharmonicity, electron-phonon coupling, and possible multigap superconductivity in the clathrate superconductors Ba 8 Si 46 and Ba 24 Si 100 : Factors behind large difference in T c
We report a detailed study of specific heat, electrical resistivity, and thermal expansion in combination with inelastic neutron and inelastic x-ray scattering to investigate the origin ofExpand
High Pressure and Superconductivity: Intercalated Graphite Cac 6 as a Model System
Superconducting CaC6 is found to exhibit two important pressure effects: (i) a large P-induced T c enhancement up to 15.1 K at 7.5 GPa, the highest T c value hitherto reported for graphiteExpand
Influence of strong-coupling and retardation effects on superconducting state in YB6 compound
Abstract In the framework of strong-coupling formalism, we have calculated the thermodynamic parameters of superconducting state in the YB6 compound. The values of critical temperature (TC) are 9.5 KExpand
Recent observation of anomalous superconducting behavior of ultrathin YBCO films and single crystals of cluster borides
We report a number of deviations from conventional behavior in the superconducting properties of ultrathin [1–3unit-cell (UC)] YBa2Cu3O7−x films sandwiched between semiconducting Pr0.6Y0.4Ba2Cu3O7−xExpand
Electronic and optical properties of ZrB12 and YB6. Discussion on electron‐phonon coupling
We report the optical properties of high-quality single crystals of low temperature superconductors zirconiumdodecaboride ZrB12 (Tc = 5.95 K) and yttrium hexaboride YB6 (Tc = 7.15 K) in the range 6Expand


Tunneling and magnetic characteristics of superconducting ZrB 12 single crystals
Bulk and surface properties of high-quality single crystals of zirconium dodecaboride have been studied in the temperature range from 4.5 K up to the superconducting transition temperature which isExpand
First-Principles Calculation of the Superconducting Transition in MgB2 within the Anisotropic Eliashberg Formalism
We present a study of the superconducting transition in MgB2 using the ab initio pseudopotential density-functional method, a fully anisotropic Eliashberg equation, and a conventional estimate forExpand
Superconductivity at 39 K in magnesium diboride
In the light of the tremendous progress that has been made in raising the transition temperature of the copper oxide superconductors (for a review, see ref. 1), it is natural to wonder how high theExpand
Quasiparticle phenomenology for thermodynamics of strong-coupling superconductors
We show that reduced critical fields, entropies, and specific heats of superconductors, regardless of “coupling-strength,” can be fitted essentially within experimental errors by curves appropriateExpand
Andreev-reflection spectroscopy in ZrB12 single crystals
We present the first results of point-contact spectroscopy (PCS) in single crystals of the boride superconductor ZrB12. The material was first characterized by AC susceptibility and resistivityExpand
Localized vibrational mode analysis of the resistivity and specific heat of LaB 6
${\mathrm{LaB}}_{6}$ and other hexaborides are inclusion compounds in which the rare earth or other metal ion is weakly bound and sits in an oversized ``cage'' of boron ions. Here we show that aExpand
On electron transport in ZrB12, ZrB2, and MgB2 in normal state
We report on measurements of the temperature dependence of resistivity, ρ(T), for single-crystal samples of ZrB12, ZrB2, and polycrystalline samples of MgB2. It is shown that the cluster compoundExpand
The Electron-Phonon Interaction
Publisher Summary The interaction of the conduction electrons with the lattice vibrations is at the center of the whole theory of the transport properties of solids. It determines the electrical andExpand
Properties of boson-exchange superconductors
The author reviews some of the important successes achieved by Eliashberg theory in describing the observed superconducting properties of many conventional superconductors. Functional derivativeExpand
Anisotropy and strong-coupling effects on the critical-magnetic-field curve of elemental superconductors
An empirical method of separating strong-coupling effects from anisotropy effects in critical-magnetic-field curves of elemental superconductors is presented. Using Clem's critical-field expressionsExpand