Ultrafast Carrier Dynamics of YBCO Films with Various In-plain Orientations Investigated by Pump-probe and Terahertz Spectroscopy

In this study, we focus on the terahertz (THz) and optical responses of superconducting YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ (YBCO) films with various in-plane orientations. We report results and analyses of THz time domain spectroscopy and time-resolved photoinduced reflectivity experiments on four in-plane orientated superconducting YBCO films grown on yttria-stabilized zirconia substrates. Our study of the transmissions of THz time domain spectroscopy indicates a higher value of conductivity at room temperature for the 0$^{\circ}$-orientation films than the 45$^{\circ}$-films. Using the optical pump-THz probe scheme, we observed combinations of positive and negative THz transmission transients relative to a thermal equilibrium level with different relaxation times of about 0.9 and 9.0 ps respectively for all samples containing 45$^{\circ}$-domains. Possible physical mechanisms will be discussed.