Thermal conductivity of the superconducting Al/Si 1% alloy below 1.2K

Abstract

The thermal conductivity of the Al/Si 1% alloy was investigated in the 0.05–1.2K temperature range. Acritical temperature,Tc≅1.2 K, was measured. BelowTc ak αexp(−b/T) law was determined down toT≅0.3 K. NearT=0.23 K, an inflexion ink suggests a resonant phonon-dislocation interaction. ForT<0.15 K, ak=λTn was found withn=2.04±0.04 and λ=(1.3±0.1) (mW/Kcm). Except for this low temperature range, in which data practically overlap those of pure Al,kAlloy is much smaller thankAl (a factor of 100 at 0.2 K). Wires (typically, O=25μm) made of this alloy are widely used in the wedge bonding of cryogenic detectors. These wires contribute to or determine the thermal conductance between the detector and the thermal bath.