MICROWAVE PROPERTIES OF STRUCTURED YBA2CU3O7-X THIN-FILMS

The microwave properties of c-axis oriented YBa2Cu3O7-x (YBCO) thin fi lms deposited by DC-magnetron sputtering were investigated between 5 a nd 20 GHz using coplanar transmission line resonators. From temperatur e dependent measurements of the quality factors of these resonators th e magnetic penetration depths lambda(L)(0) and the surface resistances R(s) were evaluated. The lowest surface resistance values were in the range between 105 muOMEGA and 200 muOMEGA at 77 K and at 6.2 GHz, res pectively. The magnetic penetration depths lambda(L)(0) were between 1 60 nm and 270 nm. The surface resistance R(s) turned out to be sensiti ve to the film quality represented by the critical cur-rent density j( c) at 77 K. From an evaluation of the temperature dependence of the re sonance frequency at low temperatures T < T(c)/2 we determined energy gap values 2DELTA(0)/k(B)T(c) between 1.2 - 2.2.