Growth Condition Dependence of Microcracks in YBCO Thin Films Pulsed Laser Deposited on (001) Substrates

The high-temperature superconductor YBCO is typically used as a thin film or coating in applications, but the brittle YBCO layer is often prone to develop small cracks, which reduce its performance. To better understand the crack formation and its connection to the uniaxial twinning state of YBCO on NdGaO₃ (001) substrates, a series of YBCO thin films has been grown by pulsed laser deposition with varying deposition temperature and growth rate. The structural properties of the samples are analyzed by atomic force microscopy and X-ray diffraction. The crack formation reduces the critical current densities, which have been measured magnetically. The results show a significant decrease in crack formation with decreased deposition temperature and also with decreased growth rate.