Probing spin glass energy landscapes with 1/f noise

We have measured the 1/f noise in the electrical resistance of thin (<10nm) CuMn wires in order to explore the spin glass state. Consistent with previous measurements, the magnitude of the 1/f noise rises rather abruptly when the system is cooled through its freezing temperature. In thin spin glass films, at temperatures near the freezing temperature, the time-dependent correlation length can grow to reach the thickness of the film on experimental timescales. This fixes the maximum barrier height, which determines the subsequent dynamics. We compare our 1/f noise data, as well as our data on the second spectrum (the noise in the 1/f noise), with previously published results on thicker CuMn films. We attribute differences to accessible time scales (frequencies) associated with the barrier heights of the thinner films.