Microstructure and Microwave Properties of YBa_2Cu_3O_<7-δ> Thin Films Grown on NdGaO_3

概要

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High-quality YBa_2Cu_3O_<7-δ> thin films have been grown on NdGaO_3 (001) substrates by in situ laser ablation. The best transition temperature determined by AC susceptibility is 88.9 K and transition width is as narrow as 0.4 K. Critical current density of 1.2×10^6A/cm^2 at 77 K was obtained. However, the loss tangent of this substrate is measured to be 3×10^<-4> at 77 K and 5 GHz which is ten times poorer than that of LaAlO_3. A 2.3 GHz resonator made from films on NdGaO_3 exhibited a low power Q of 4500 which is very close to the calculated limit based on the loss tangent data. The microwave performance is thus severely limited by the substrate loss in our test geometries.
社団法人応用物理学会の論文
1991-08-01