THERMAL-RESISTANCE OF NORMAL - SUPERCONDUCTOR INTERPHASE BOUNDARIES

We have determined the thermal resistance of normal-superconductor (N- S) interphase boundaries in Sn (as in In, Pb, Tl) by measuring the the rmal resistivity of a regular Landau lamellar structure of intermediat e state (known from a separate magneto-optical experiment) with its la mellas perpendicular to the heat current. In the temperature range whe re the phonon heat conduction is still neglegible and DELTA(T) much gr eater than k(B)T the N-S interphase thermal resistance shows the exp(D ELTA/k(B)T) temperature dependance predicted by Andreev reflection of nearly all the quasiparticles at the boundary.