Suppression of Commensurability Peaks in AN Andreev Reflecting Antidot Billiard

We present magnetotransport data on antidot arrays with Andreev reflecting boundaries. The samples consist of niobium filled antidot lattices in a high-mobility InAs/AlGaSb heterostructure. They were fabricated with wet chemical etching or a selective SiCl₄-based reactive ion etch and sputtering. When the Nb dots are superconducting we observe a strong reduction of the commensurability peaks, which is explained in terms of the classical Kubo formula. Ideally, despite the chaotic motion in real space the commensurability peaks should be completely suppressed.