Materials aspects of integrated high Tc dc-SQUID magnetometer fabrication

Abstract

An integrated high Tc de-SQUID magnetometer is being developed. It has in total 10 layers of five different materials. Various materials aspects of the fabrication process will be discussed, especially the smoothness of the films and the techniques to obtain smooth edges. Cross-overs and superconducting window 9contacts were fabricated. The critical temperature of the window-contact is 84K (jc(77K)=2.10"A/cm -) and the resistivity of the insulating SrTiO 3 layer in the cross-over is 6-10 f~cm at 77K. The complete coil often shows a small resistive component down to about 50K. Ramp type and bi-epitaxial grain boundary de-SQUIDs show voltage modulation up to 65K and 79K, respectively. Efforts to fabricate an integrated high T e de-SQUID magnetometer will be discussed.

High-transition-temperature superconducting quantum interference devices

“…The first multilayer flip-chip magnetometers were reported almost simultaneously by groups at Berkeley (Miklich et al, 1991;Wellstood et al, 1992) and IBM . Since this early work, many groups have described the fabrication of multiturn flux transformers (Freltoft et al, 1993;Hilgenkamp et al, 1993) and the operation of flip-chip magnetometers at 77 K Miklich et al, 1993;Roas et al, 1993;, Keene et al, 1995Dantsker et al, 1995;Fife et al, 1995;Scharnweber et al, 1995;Schilling et al, 1995;Kugai et al, 1996).…”

Bi-epitaxial template grain boundaries with different in-plane angles on (100) MgO substrates

“…The highest modulation voltage we have observed was 90 ~tV at 4.2 K, with a flux to voltage transfer 8V/Sd~ ---310 ~tV/~5 o. More details of the electrical measurements will be published elsewhere [9].…”