A new epitaxial BaSnO_3 buffer layer for YBa_2Cu_3O_(7-#delta#) thin films on MgO substrates

摘要

45beg grain boundaries, which drastically increasesurface resistance (R_s) in superconducting YBa_2Cu_3O_(7-#delta#) films for microwave devices on MgO substrates, areeliminated using a new buffer layer of BaSnO_3. BaSnO_3 bufferlayers and YBa_2Cu_3O_(7-#delta#) films are grown by ArFpulsed laser deposition. Epitaxial relationships among BaSnO_3,YBa_2Cu_3O_(7-#delta#) and MgO are confirmed by x-ray#phi#-scanning. The R_s values of the YBa_2Cu_3O_(7-#delta#)films are measured using a dielectric resonator with 22 GHzTE011 mode. The epitaxial YBa_2Cu_3O_(7-#delta#) filmsgrown on BaSnO_3 buffered MgO substrates show lower R_sthan YBa_2Cu_3O_(7-#delta#) films directly grown on MgOsubstrates. The BaSnO_3 buffer layer which enablesYBa_2Cu_3O_(7-#delta#) films to grow without 45beg grainboundaries at a optimum film growth condition is attractive formicrowave applications.