1/f noise in the resistive transition region of high-temperature superconductor YBCO microbridged thin films

The measurement of the normalized noise power spectral density (S n (f)=S v (f)/V 2 ) of the YBCO microbridge sows 1/f alpha dependence. The key features of the present measurements are as follows: in the normal state, S n (f) is several orders of magnitude larger than the value predicted by Hooge (1969); near T c , S n (f) increases by several orders of magnitude and alpha approaches 2; the noise power increases in a magnetic field near T c . This enhancement of S n (f) seems to be related to fluctuation at the phase transition due to the instability of Cooper pair formation and breaking.