Andreev reflection in unitary and non-unitary triplet states

The quasiparticle reflection and transmission properties at normal conductor-superconductor interfaces are discussed for unitary and non-unitary spin triplet pairing states recently proposed for Sr_2RuO_4. We find resonance peaks in the Andreev reflection amplitude, which are related to surface bound states in the superconductor. They lead to conductance peak features below the quasiparticle gap in the superconductor. The position of the peaks depends on the angle of the incident quasiparticles in a different way for unitary and non-unitary states. Based on this observation we propose a possible experiment which allows to distinguish between the two kinds of superconducting states.