Crossover from fractal to non-fractal flux penetration in vicinal Tl₂Ba₂CuO_6+δ thin films

The role of anisotropy on magnetic flux penetration and critical current density jc in c-axis epitaxial Tl2Ba2CuO6+δ (T12201) films is investigated by magneto-optics. Thin films of T12201 are deposited by a sputtering technique on vicinal (001) SrTi03 substrates with miscut angles of 0.5 and 2.5 degrees and patterned into various shapes. Circular samples are used to determine the current anisotropy axis, whereas square samples allow to evaluate the amplitude of this anisotropy. A cross-over from fractal to uniform anisotropic flux penetration is observed with increasing miscut angle.