High-T_c, multilevel edge junction superconducting quantum interference devices with SrTiO₃ barriers operating at 77 K

All high-Tc, multilevel edge junction superconducting quantum interference devices (SQUIDs) which now operate at 77 K have been fabricated using laser-ablated YBaCuO electrodes and in situ laser-ablated SrTiO 3 for the barrier material. Devices with a SQUID inductance of about 70 pH have a peak to peak voltage swing, VΦ, up to 8 μV (dV/dΦ≅25 μV) and a flux noise (SΦ) of about 3×10-10 Φ20/Hz in the white noise region. IcRn, products for these devices are about 35 μV at 77 K with Ic in the range of 3-100 μA and operation to temperatures as high as 84 K observed. Scaling of the junction conductance and critical current with junction size has been measured on many devices and we observe an IcRn product that varies approximately as J0.89c.