SYSTEMATICS OF TRANSPORT ANISOTROPY IN SINGLE-DOMAIN LA2-XSRXCUO4 FILMS

The ability to control the tilt angle of CuO2 planes with respect to the film surface has led to successful synthesis of single-domain, epitaxial La2-xSrxCuO4 filMS of (103) and (109) orientations corresponding to tilt angles of 21-degrees and 49-degrees, respectively. The systematics of the c-axis resistivity and transport anisotropy rho(c)/rho(ab) have been studied as a function of Sr doping varying from 0.04 to 0.34 over 2 less-than-or-equal-to T less-than-or-equal-to 800 K. The temperature dependence of the c-axis resistivity evolves from semiconductinglike behavior in the lightly doped and optimally (superconducting) doped regions (x less-than-or-equal-to 0.15) to metallic behavior in the heavily doped region (x greater-than-or-equal-to 0.25), displaying a notable discontinuity of the slope at the tetragonal-orthorhombic phase transformation. The crossover from two-dimensional metallic transport to strongly anisotropic three-dimensional metallic transport was observed near the superconducting phase boundary (x is similar to 0.22). The evolution of transport anisotropy rho(c)/rho(ab) closely resembles the evolution of the electronic orbital character of doping-induced holes, hence suggesting a connection between the two-dimensional electronic structure and superconductivity.