HTSC JOSEPHSON-JUNCTIONS AND DC SQUIDS ON SRTIO3 BICRYSTAL SUBSTRATESGROWN BY FLOATING-ZONE METHOD

A new approach to the fabrication of a SrTiO3 bicrystal substrate base d on the technology of growing by floating zone method natural SrTiO3 bicrystals with misorientation angles 24 degrees and 37 degrees has be en developed. Thin Nm YBCO Josephson junctions and de SQUIDs on SrTiO3 bicrystal substrates were fabricated and studied at T=77 H. A critica l current density j(c) and IcRn product for the junctions with misorie ntation angle alpha=24 degrees were close to 2x10(4) A/cm(2) and 190-2 60 mu V respectively, while for alpha=37 degrees it were found that j( c) approximate to 2x10(3) A/cm(2) and IcRn approximate to 90-120 mu V. The de SQUIDs were made with typical inductances 20-80 pH, critical c urrents of 20-150 mu A and resulting voltage modulation 10-40 mu V Noi se measurements performed at 77 K revealed low 1/f noise with cut-off frequency about 10 Hz.