Weak localization in a distribution of magnetic flux tubes

Thin gates of type-II superconducting materials have been prepared on top of the two-dimensional electron gas in a GaAs/AlGaAs heterostructure. In an applied magnetic field the flux distribution at the electron gas takes the form of flux tubes which are much narrower than an electron phase coherence length. We observe a qualitatively new weak-localization magnetoconductance for small fields proportional to {}B{}, in contrast to the B² homogeneous result and in semiquantitative agreement with the theory of Rammer and Shelankov.