Persistent currents in a GaAs-AlGaAs single loop

We have measured the magnetization of a mesoscopic single loop etched in a GaAs-GaAlAs heterojunction of high mobility. We have fabricated a SQUID detector of size comparable to the ring to achieve a good coupling. The all experimental set-up in fabricated on a single chip by electron beam lithography. We measured a typical current of 4 ± 2nA which is for the first time in good agreement with theory.