VORTEX FLUCTUATIONS, TILT MODULUS AND RESISTIVITY OF LAYERED HIGH-T(C) SUPERCONDUCTORS

We investigate the influence of the layered structure of high-T(c) superconductors on the tilt modulus and on flux line melting and calculate the voltage-current relation in a magnetic field near the Kosterlitz-Thouless temperature T(KT). The tilt modulus depends on the magnetic and Josephson interlayer coupling energy. For a single flux line with a local distortion, the magnetic contribution is a factor (d/lambda)2 and the Josephson contribution a factor m/M smaller than in an isotropic continuum. Here, d is the interlayer spacing, lambda the London penetration depth in the ab-planes, and M and m are the electron masses in c- and ab-directions, respectively. A flux line lattice with the lattice constant a0 greater-than-or-equal-to 2-lambda melts at the temperature T(KT) at which independent point-like vortex-antivortex pairs dissociate. For sufficiently large fields, the exponents a(T), of the voltage-current relation V approximately I(a)(T), and b(T), of the voltage-field relation V approximately H(b)(T) for I --> 0, are connected by b(T) = a(T)/2.