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Search for incoherent tunnel fluctuations of the magnetisation in nanoparticles of artificial ferritin

C. Gilles·P. Bonville·K. K. W. Wong·S. Mann
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Abstract

The magnetic behaviour of nanoparticles of antiferromagnetic ferritin, with a mean Fe loading of 410 atoms per core, has been investigated by 57Fe Mossbauer absorption spectroscopy down to very low temperature (34mK). In previous experi- ments of frequency dependent magnetic susceptibility and magnetic noise performed at 25mK in similar samples, it was claimed that a resonance at a frequency of about 10**8 Hz, due to a macroscopic coherent state, had been observed. However, our search of incoherent tunnel fluctuations around 10**8 Hz using 57Fe Mossbauer spectroscopy, whose "window" of measurement of fluctuation frequencies lies in this frequency range, was unsuccessful. This casts a doubt about the previous observa- tion of macroscopic quantum coherence in ferritin.

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C. Gilles, P. Bonville, K. K. W. Wong, S. Mann. 2000-07-06. Search for incoherent tunnel fluctuations of the magnetisation in nanoparticles of artificial ferritin. https://arxiv.org/abs/cond-mat/0007090

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