We study the magnetic relaxation rate Gamma of the single-molecule magnet Mn_{12}-tBuAc as a function of magnetic field component H_T transverse to the molecule's easy axis. When the spin is near a magnetic quantum tunneling resonance, we find that Gamma increases abruptly at certain values of H_T. These increases are observed just beyond values of H_T at which a geometric-phase interference effect suppresses tunneling between two excited energy levels. The effect is washed out by rotating H_T away from the spin's hard axis, thereby suppressing the interference effect. Detailed numerical calculations of Gamma using the known spin Hamiltonian accurately reproduce the observed behavior. These results are the first experimental evidence for geometric-phase interference in a single-molecule magnet with true four-fold symmetry.
@article{arxiv.1210.6105,
title = {Geometric-phase interference in a Mn_{12} single-molecule magnet with four-fold rotational symmetry},
author = {S. T. Adams and E. H. da Silva Neto and S. Datta and J. F. Ware and C. Lampropoulos and G. Christou and Y. Myaesoedov and E. Zeldov and Jonathan R. Friedman},
journal= {arXiv preprint arXiv:1210.6105},
year = {2013}
}
Comments
version accepted by PRL; added inset to Fig. 1, added three references and a footnote; other minor changes; 5 pages, 4 figures