Evidence for resonant tunneling of magnetization in Mn 12 acetate complex

J. M. Hernandez*, X. X. Zhang, F. Luis, J. Tejada, Jonathan R. Friedman, M. P. Sarachik, R. Ziolo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

143 Scopus citations

Abstract

We have measured the dc magnetization at low temperatures of tetragonal crystals of Mn 12 acetate complex [Mn 12O 12(CH 3COO) 16(H 2O) 4], a material composed of a large (Avogadro's) number of identical magnetic molecules, each of spin 10. Exchange coupling between Mn ions within each molecule is very strong, while the interaction between molecules is negligible. A large, uniaxial anisotropy (∼60 K) gives rise to a doubly degenerate ground state corresponding to spin projections of ±10 along the easy axis (c axis); hysteretic behavior is found below a blocking temperature T b∼3 K. Based on measurements of oriented crystallites at temperatures between 1.7 and 3.2 K, we report strong evidence for resonant tunneling of the magnetization: periodic steps in the hysteresis loop, and periodic marked increases in the magnetic relaxation rate at the magnetic fields corresponding to these steps. A total of seven increases in the relaxation rate were found within the temperature range of our experiments with a period of 0.46 T; we suggest that many more such steps would be found at lower temperatures. We attribute these observations to thermally assisted resonant tunneling of the magnetization and propose a detailed model to account for our results.

Original languageEnglish (US)
Pages (from-to)5858-5865
Number of pages8
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume55
Issue number9
StatePublished - Mar 1 1997
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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