Theory of 1/fmagnetic flux noise in high-Tcsuperconductors

A theoretical model is proposed to explain the magnitude of excess 1/f magnetic flux noise in high-${\mathit{T}}_{\mathit{c}}$ superconducting SQUID’s. Based on a model for 1/f noise generation due to the multiple elastic scattering of quasiparticles with disordered mobile vortices, we show that the 1/f flux noise magnitude has the following features: It increases with T below ${\mathit{T}}_{\mathit{c}}$, sharply falls off with T above ${\mathit{T}}_{\mathit{c}}$, and decreases with an increasing energy gap. Its magnetic-field dependence is also shown to be inversely proportional to the square of the voltage-to-flux transfer function. Our results are shown to be in good agreement with recent experimental measurements.