Superconducting quantum interference device based on MgB2 nanobridges

The superconductor MgB2, with a transition temperature of 39 K, has signifi cant potential for future electronics. An essential step is the achievement of Josephson circuits, of which the superconducting quantum interference d evice (SQUID) is the most important. Here, we report Josephson quantum inte rference in superconducting MgB2 thin films. Modulation voltages of up to 3 0 muV are observed in an all-MgB2 SQUID, based on focused-ion-beam patterne d nanobridges. These bridges, with a length scale < 100 nm, have outstandin g critical current densities of 7x10(6) A/cm(2) at 4.2 K. (C) 2001 American Institute of Physics.