engleski

Superparamagnetism of Magnetic Nano-Clusters in Hf-Fe Amorphous Alloy

The magnetic behaviour of the amorphous alloy Hf(57)Fe(43) is expected to be superparamagnetic. The iron concentration is just below the threshold for establishing magnetic long range order in Hf(100-x)Fe(x) amorphous system. Relatively large magnetic moments of iron nanoclusters formed in the nonmagnetic host are the origin of superparamagnetic behaviour. Detailed measurements including magnetic hysteresis loops, dependence of magnetic moment on temperature and the relaxation of magnetization are performed. They confirm the blocking of magnetic moments of superparamagnetic clusters at lower temperatures. This is accompanied by slow temperature-dependent magnetic relaxation. Using the model of thermal relaxation it is found that clusters are of the approximate size 15-20nm. Quantum tunneling of their magnetic moments was not observed down to 1.8K.

Superparamagnetism; magnetic nano-clusters

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