Electron transmission in normal metal/heavy-fermion superconductor junctions:: A two-band model

The Andreev reflection between a normal metal (N) and a heavy-fermion superconductor (HFS) is studied and the boundary conditions for the electron's wave function in the two systems are established in the framework of a two-band model for the HFS. Hence, in a simple and explicit way, we show that the mass enhancement factors in the heavy-fermion metal do not cause impedance at the N/HFS interface, which is in accordance with arguments previously presented. We also present an extension of the theory to a two-fluid model for the heavy fermion, which is possibly applicable to, e.g., CeCoIn5.