Fractal dimension of structural inhomogeneities in granular YBCO superconductor in magnetic field

Fractal Boundaries of Vortex Pinning Clusters in Copper-oxide Superconductors in Magnetic Field

“…Fractal properties have been found in many copper-oxide hightemperature superconductors (HTSC) experimentally based on resistive measurements [1,2] and the direct supervision of using a magneto-optical technique [3][4][5]. Modeling of properties copperoxide HTSC is also possible with the help consideration of their fractal features [6][7][8].…”

“…The dependence of the fractal dimension of the normal phase clusters on the magnetic field strength. Black circles are the data obtained in paper [8], solid line is empirical dependence (equation (1)) Fig. 2 shows the experimental dependence of the amplitudes of the first voltage harmonic V 1 for YBCO sample on the magnetic field strength (black circles) for different values of DC.…”

“…In the article [8] it was found that the DC magnetic field strongly influences on the fractal dimension of the boundaries of the normal phase clusters. This is due to the formation of weak links and structural defects generated easily in HTSC because of the short coherence length in these materials.…”

“…All of these factors significantly associated with the fractal properties of the boundaries of the normal phase clusters. Such clusters are formed as by irradiating the samples with heavy ions, and during film growth or sintering of polycrystalline bulk samples [8][9][10][11].…”

“…Fig. 1 shows the dependence of the fractal dimension of the boundaries of the normal phase clusters D on strength of DC magnetic field H. The dependence D(H), obtained in [8] (black circles), was approximated by the function (solid line):…”