Devices using high Tc superconductors

This patent describes a superconducting quantum interference device (SQUID) device operable at temperatures greater than 60 degrees K. It comprises a layer of high Tc superconducting material capable of exhibiting superconductivity at temperatures greater than 60 degrees K., implanted regions of the layer having a sufficiently damaged structure that the implanted regions are nonsuperconducting, nonimplanted regions of the layer which have high Tc superconductivity and form a superconductivity loop, wherein the implanted and nonimplanted regions have substantially coplanar surfaces, wherein the implanted regions constrict the width of the loop in at least two locations therein, the constriction being sufficient to form weak links at each of the locations, wherein the superconducting loop including the weak links operates as a DC SQUID device which electrical currents exist therein at temperatures greater than 60 degrees K