Experimental observation of persistent currents in GaAs-AlGaAs single loop

We report measurements of the magnetic response of a GaAlAs/GaAs mesoscopic ring. We have developed a dedicated SQUID technique where sample and SQUID are on the same chip. We have detected a periodic signal, with a period h/e, which is the signature of a persistent current with an amplitude 4\ifmmode\pm\else\textpm\fi{}2 nA, in good agreement with current theories.