Effect of growth-induced linear defects on high frequency properties of pulse-laser deposited YBa2Cu3O7-delta films

Growth-induced linear defects are shown to strongly affect the microwave su rface resistance, R,, of highly biaxially oriented high temperature superco nductor (HTS) YBa2Cu3O7-delta (YBCO) films. Measured R-s(77 K) turned out t o be 4-5 times higher than in single crystals. The films were deposited by modified pulse-laser technique, J(c)(77 K) = (3 - 6) x 10(6) A/cm(2), onto LaAlO3 substrates. R-s(T) was measured at 134 GHz and 20-100 K. TEM/HREM st udy of YBCO films deposited at T-s = 750 degreesC-780 degreesC revealed a r eduction of edge dislocation density with T-s increase (from 2.10(11) to 10 .(10) lines/cm(2)). YBCO films deposited at T-s = 780 degreesC exhibited th e smallest R-s(77 K, 134 GHz) < 120 m Ohm and the lowest density of disloca tions detected by HREM and X-ray analysis. A nature of the dislocation effe ct is discussed within a model of local anisotropic elastic deformation in a vicinity of dislocation cores, where T-c variation and an enhancement of normal quasiparticle density are significant.