Two-Dimensional Phase Fluctuation in High-Tc Superconductor under Magnetic Field
Two kinds of power laws, V∝I n(T,H) and V∝H m(T, I), are observed in high Tc superconducting ErBa2Cu3 O7 - x films. The Nelson-Kosterlitz jumps and the related new kinks are found in the temperature dependences of the respective exponents n and m, giving direct evidences of the Kosterlitz-Thouless transition. These behaviors are the results of vortex-antivortex pair excitation caused by the phase fluctuation on the each CuO2 plane. Dynamics of the pair excitation is turned out to be strongly affected by an applied magnetic field. The observed power laws in a magnetic field with an arbitrary direction suggest that the pair excitation in a magnetic field is related to the flux entanglemant state.
KeywordsMagnetic Field Applied Magnetic Field Vortex Line Flux Line Phase Fluctuation
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