Micro-Hall magnetometry studies of thermally assisted and pure quantum tunneling in single molecule magnet Mn12-acetate

Louisa Bokacheva, Andrew D. Kent, Marc A. Walters

Research output: Contribution to journalArticlepeer-review

Abstract

We have studied the crossover between thermally assisted and pure quantum tunneling in single crystals of high spin (S = 10) uniaxial single molecule magnet Mn12 using micro-Hall effect magnetometry. Magnetic hysteresis experiments have been used to investigate the energy levels that determine the magnetization reversal as a function of magnetic field and temperature. These experiments demonstrate that the crossover occurs in a narrow ( ∼ 0.1 K) or broad ( ∼ 1 K) temperature interval depending on the magnitude and direction of the applied field. For low external fields applied parallel to the easy axis, the energy levels that dominate the tunneling shift abruptly with temperature. In the presence of a transverse field and/or large longitudinal field these energy levels change with temperature more gradually. A comparison of our experimental results with model calculations of this crossover suggests that there are additional mechanisms that enhance the tunneling rate of low-lying energy levels and broaden the crossover for small transverse fields.

Original languageEnglish (US)
Pages (from-to)1717-1721
Number of pages5
JournalPolyhedron
Volume20
Issue number11-14
DOIs
StatePublished - May 30 2001

Keywords

  • Hall-effect magnetometry
  • High-spin clusters
  • Hysteresis
  • Quantum tunneling
  • Single molecule magnets

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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