ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
We report on the magnetization noise in a soft ferromagnetic alloy for frequencies f〈10 Hz, temperatures T〈4.2 K, and excitation field amplitudes 〈150 μA/m. The spectra agree, without any adjustable parameter, with the fluctuation dissipation formula and the measured complex susceptibility of the material. The spectra show a 1/f shape coming from a frequency-independent imaginary susceptibility χ‘0. χ‘0 is found to be proportional to T above ≈2.5 K but tends to be independent of T below this value. After annealing the sample to relieve the internal stresses, χ‘0 is found nearly temperature independent above ≈2.5 K and to sharply increase by decreasing the temperature below that value. We discuss these findings in terms of the hopping of the magnetization by activation or tunneling.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.358257