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

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Abstract
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 SrTiO3 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.