Thermal conductivity of the normal and superconducting Al/Si 1% alloy

The thermal conductivity of the Al/Si 1% alloy was investigated in the 0.05-1.2 K temperature range. Wires (typically circle divide = 25 mu m) 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. Measurements in both the normal state and in the superconducting state are presented. A critical temperature, T-c = (1.20 +/- 0.02)K, was measured. In the superconducting state, the following results were obtained: i) below T-c, a k proportional to exp(-beta/T) law was determined down to T similar or equal to 0.3 K; ii) for T < 0.2 K, a k = aT(n) was found with n similar or equal to 2. In the normal state, a k = aT + bT(2) law was determined, showing an electronic contribution and a lattice component. For both cases, the results are compared to the thermal conductivity of pure Al.