Magnetic and electric properties of magnetron-sputtered YBCO/LSMO and LSMO/YBCO double layers

摘要

Magnetic and electric properties of epitaxially grown YBa2CuO7-x(YBCO)/La0.7Sr0.3MnO3(LSMO) and LSMO/ YBCO structures prepared by off-axis and faced-target magnetron sputtering deposition on SrTiO3 [1 0 0] substrates without intermediate buffer are investigated. The possibility is demonstrated to fabricate soft (with low coercive force H-c = 25 Oe) films, independent of the temperature used, and 'tuned-soft' (with coercive force H. up to 200 Oe), the latter being achieved by heating substrate non-uniformly during deposition. A novel technique is realised for substrate heating during deposition, whereby the substrate is separated from the heater by thin (0.2 mm in diameter) quartz fibres, which allow several deposition cycles for one sample in different vacuum installations. At 77 K the superconducting film has T(c)similar to86 K and J(c)similar to0.7 x 10(6) A/cm(2) as a bottom layer, and T(c)similar to88 K and J(c)similar to1.7 x 10(6) A/cm(2) as a top layer (the optimal stand-alone YBCO films have T(c)similar to90 K and J(c)similar to(2.5-5) x 10(6) A/cm(2) at 77 K). The magnetic measurements of the in-plane magnetic moment by SQUID magnetometer gave M=0.6-1.2Am(2) at H = 200 Oe. The results demonstrate the possibility of depositing double-layer combinations of YBCO/LSMO films with reproducible high crystalline quality, without an intermediate buffer for spintronics applications. (C) 2004 Elsevier Ltd. All rights reserved.