RE-123 thin films for microwave applications

Abstract

Large area REBa 2Cu 3O 7 (RE-123; RE=rare earth) thin films have been grown by reactive thermal coevaporation. The work was targeted to identify compounds with superior high frequency properties compared to Y-123 films. As a general trend we found that with increasing RE ionic radius the transition temperature as well as the tendency for cracking increased. No such trend was recognizable for the surface resistance. Dy-123 and Nd-123 films exhibit lower surface resistance at 77 K than Y-123 films at the same thickness. On sapphire substrates however Y-123 films are advantageous because they are less susceptible to thermal cracking.