Chaotic motion and suppression of commensurability effects in an Andreev antidot billiard

We investigated antidot lattices with Andreev reflecting boundaries both in experiment and theory. The samples consist of arrays of niobium-filled antidots in an InAs-based heterostructure. The quality of the Nb–InAs contact could be controlled by an in situ Ar+ sputter cleaning step. In samples with a high transparency contact, we find a strong reduction of the resistance around B=0 and a suppression of the commensurability peaks. These observations can be explained in a classical Kubo approach by including Andreev reflection and assuming a magnetic-field-dependent Andreev reflection probability.