Thermal conductivity of superconducting MgB₂

Abstract

Thermal conductivity of superconducting MgB 2 was studied in both the superconducting and the normal state region. The latter is almost equally determined by the electronic -and the lattice contribution to the total thermal conductivity. In the superconducting state, however, the lattice contribution is larger. The electronic thermal conductivity below T c was derived from the experimental data considering the Bardeen-Rickayzen-Tewordt theory together with the model of Geilikman. The analysis shows that electron scattering on static imperfections dominates.

Thermal conductivity of single-crystallineMgB2

“…The κ(T ) values are about an order of magnitude higher than previously reported for polycrystalline samples. 23,24,25,26 Also the overall temperature dependence of κ is quite different from those earlier data. Instead of a monotonous increase with temperature we note a distinct maximum of κ(T ) at T ∼ 65 K. The cause of these differences is obviously the strong influence of intergrain boundaries on the heat transport in polycrystals, which masks the intrinsic mechanisms of quasiparticle scattering.…”

“…23,24,25,26 This observation is quite unusual for superconductors with nonnegligible phonon heat transport, because the opening of the superconducting gap rapidly reduces the rate of phonon scattering on electrons and should lead to a fast increase of κ ph below T c . The assumptions that either the phonon-electron scattering is much weaker than phonondefect scattering, or that κ ph is negligibly small in the vicinity of T c , which, in principle, might explain the absence of a κ(T ) feature at T c , are all incompatible with the observation that applying a relatively weak external magnetic field of 0.63 kOe, introducing some additional quasiparticles in the cores of vortices, considerably reduces the thermal conductivity at intermediate temperatures (see Fig.…”

Physical property characterization of bulk MgB2 superconductor

“…In earlier reports the κ(T) of MgB 2 did not exhibit any sign of superconducting transition [13,33,38,42,45,51,52,55,56]. However on the contrary, recently the κ(T) data on pure and substituted MgB 2 single crystals had shown an anomaly in thermal conductivity below T c [57].…”

Magnetic field dependence of the density of states in the multiband superconductorβ−Bi2Pd

“…The upper critical field shows a positive curvature, instead of the negative curvature expected within single-gap s-wave BCS superconductivity [10,[15][16][17][18][19][20][21][22]. The same occurs * Corresponding author: hermann.suderow@uam.es in many different compounds, including heavy fermions, borocarbides, and Fe-based superconductors [11,[23][24][25][26][27][28][29]. So far, the increased density of states and positive curvature of H c2 close to T c have been explained through multigap superconductivity.…”