Abstract
Staircaselike hysteresis loops of the magnetization of a single crystal are observed at subkelvin temperatures and low field sweep rates. This behavior results from quantum dynamics at avoided level crossings of the energy spectrum of single ions in the presence of hyperfine interactions. Enhanced quantum relaxation in constant transverse fields allows the study of the relative magnitude of tunnel splittings. At faster sweep rates, nonequilibrated spin-phonon and spin-spin transitions, mediated by weak dipolar interactions, lead to magnetization oscillations and additional steps.
- Received 12 February 2001
DOI:https://doi.org/10.1103/PhysRevLett.87.057203
©2001 American Physical Society