Low-temperature magnetic hysteresis in Mn12 acetate single crystals

A. D. Kent, Yicheng Zhong, L. Bokacheva, D. Ruiz, D. N. Hendrickson, M. P. Sarachik

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Precise magnetic-hysteresis measurements of small single crystals of Mn12 acetate of spin 10 have been conducted down to 0.4 K using a high-sensitivity Hall magnetometer. At higher temperature (> 1.6 K) step-like changes in magnetization are observed at regularly spaced magnetic-field intervals, as previously reported. However, on lowering the temperature the steps in magnetization shift to higher magnetic fields, initially gradually. These results are consistent with the presence of a higher-order uniaxial magnetic anisotropy (fourth order in Sz), first observed by EPR spectroscopy, and thermally assisted tunnelling with tunnelling relaxation occurring from levels of progressively lower energy as the temperature is reduced. At lower temperature an abrupt shift in step positions is found. We suggest that this shift may be the first evidence of an abrupt, or first-order, transition between thermally assisted and pure quantum tunnelling, suggested by recent theory.

    Original languageEnglish (US)
    Pages (from-to)521-527
    Number of pages7
    JournalEurophysics Letters
    Volume49
    Issue number4
    DOIs
    StatePublished - Feb 11 2000

    ASJC Scopus subject areas

    • Physics and Astronomy(all)

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