CRITICAL THERMAL-BOUNDARY RESISTANCE OF HE-4 ABOVE AND BELOW T-LAMBDA - RENORMALIZATION-GROUP THEORY

We present a unified description of the critical thermal boundary resistance (Kapitza resistance) R(K) of He-4 above and below T-lambda. A local renormalization procedure is introduced that is well adapted to the inhomogeneous situation induced by the Dirichlet boundary conditions for the order parameter. The critical temperature dependence of R(K) is calculated without an adjustment of parameters. The inadequacy of previous hydrodynamiclike approaches is discussed. The advantage of our local renormalization-group treatment is elucidated for the examples of the static surface energy and surface specific heat. Our theoretical result for R(K) is compared with experimental data above and below T-lambda. Good quantitative agreement is found below T-lambda. Above T-lambda the measured effective exponent of R(K) is consistent with our prediction but the magnitude of R(K) differs considerably.