Dynamic critical properties of the vortex-glass transition derived from angular-dependent properties of La 2 − x Sr x CuO 4 films

We present resistivity data on a high-quality ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4\ensuremath{-}\ensuremath{\delta}}$ film measured in a magnetic field of 1 T applied at an angle $\ensuremath{\delta}$ to the c axis. Using these data, the influence of the orientation of the magnetic field and the effective mass anisotropy on the vortex-glass transition can be studied. The variation of $\ensuremath{\delta}$ for a fixed magnitude of the magnetic field allows us to investigate the critical properties of interest, including the 2D-to-3D crossover and the 3D vortex glass-to-fluid transition, as the temperature is decreased. The data are well described by the scaling theory for the d.c. resistivity of an anisotropic superconductor in a magnetic field applied at an angle $\ensuremath{\delta}$ to the c axis. This scaling includes the critical properties close to and at the vortex-glass transition. The main results include (i) evidence of a Kosterlitz\char21{}Thouless transition in zero field, and (ii) a 2D-to-3D crossover at $H=1$ T as the temperature is decreased below the zero-field transition temperature, leading to the vortex fluid-to-vortex glass transition in $D=3$ characterized by the dynamic critical exponent $z\ensuremath{\approx}57.$