Magnetic Field Dependence of Voltage Noise in Y₁Ba₂Cu₃O_7-x Ceramic Superconductor Film

Abstract

We present an alternative procedure for solving the eigenvalue problem of replicated transfer matrices describing disordered spin systems with (random) 1D nearest neighbour bonds and/or random fields, possibly in combination with (random) long range bonds. Our method is based on transforming the original eigenvalue problem for a 2 n × 2 n matrix (where n → 0) into an eigenvalue problem for integral operators. We first develop our formalism for the Ising chain with random bonds and fields, where we recover known results. We then apply our methods to models of spins which interact simultaneously via a onedimensional ring and via more complex long-range connectivity structures, e.g., (1 + ∞)-dimensional neural networks and 'small-world' magnets. Numerical simulations confirm our predictions satisfactorily.

Dynamic of vortices in YBa2Cu3O7–δ single crystal near the temperature of the vortex glass transition by the use of voltage noise measurements

“…The second is the superconducting fluctuations model [6]; however, it does not exist any theory to relate them directly to the observed noise. The third is the magnetic flux noise [7]. This source is relevant to SQUID, but may or may not be directly related the transport measurement.…”