Probing AgMn spin glass thin film with 1/f noise*

Analysis of electronic 1/f noise data can provide the energy barrier distribution of the spin glass state in thin films.  In overly simple terms, the electronic noise spectrum of a spin glass is related to the differences in the spin configurations that occur by transitions over the energy barriers. The power spectral density is proportional to 1/f^α and the exponent, α, of the noise spectrum can be used to determine the energy barrier distribution. In general, the noise measurements are limited to a frequency bandwidth and this limitation requires the temperature dependence of the exponent to provide a more complete barrier distribution; the resulting distribution is a zero temperature distribution. We have used this technique to determine the energy barrier distribution for thin films of the spin glass alloy AgMn (12 at.%) for which the solid solubility for Mn is larger than CuMn. In our measurements, different thicknesses were investigated but here we focus on the results for a 40nm thick film. In addition to the AgMn results, we make a comparison with the results from similar measurements on CuMn.