title: Muon spin rotation studies of spin dynamics at avoided level crossings in LiY0.998Ho0.002F4.
abstract: We have studied the Ho3+ spin dynamics for LiY0.998Ho0.002F4 via the positive muon (mu+) transverse field depolarization rate lambdaTF as a function of temperature and magnetic field. We find sharp minima in lambdaTF(H) at fields for which the Ho3+ ion system has field-induced (avoided) level crossings. The reduction scales with calculated level repulsions, suggesting that mu+ depolarization by slow fluctuations of nonresonant Ho3+ spin states is partly suppressed when resonant tunneling opens new fluctuation channels at frequencies much greater than the muon precession frequency.
authors.affiliation: Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Graf
authors.forename: J
authors.initials: J
authors.lastname: Lago
authors.forename: A
authors.initials: A
authors.lastname: Lascialfari
authors.forename: A
authors.initials: A
authors.lastname: Amato
authors.forename: C
authors.initials: C
authors.lastname: Baines
authors.forename: S R
authors.initials: SR
authors.lastname: Giblin
authors.forename: J S
authors.initials: JS
authors.lastname: Lord
authors.forename: A M
authors.initials: AM
authors.lastname: Tkachuk
authors.forename: B
authors.initials: B
authors.lastname: Barbara