Muon spin rotation studies of spin dynamics at avoided level crossings in LiY0.998Ho0.002F4

TL;DR

This study investigates how muon spin depolarization rates in LiY0.998Ho0.002F4 are affected by magnetic field-induced avoided level crossings, revealing the influence of resonant tunneling on spin dynamics.

Contribution

It provides new insights into Ho3+ spin behavior at avoided level crossings using muon spin rotation, highlighting the suppression of depolarization due to resonant tunneling.

Findings

Depolarization rate lambda_TF(H) drops sharply at specific fields

Reductions scale with calculated level repulsions

Resonant tunneling opens new fluctuation channels

Abstract

We have studied the Ho3+ spin dynamics for LiY0.998Ho0.002F4 through the positive muon (mu+) transverse field depolarization rate lambda_TF as a function of temperature and magnetic field. We find sharp reductions in lambda_TF(H) at fields of 23, 46 and 69 mT, 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 non-resonant Ho3+ spin states is partially suppressed when resonant tunneling opens new fluctuation channels at frequencies much greater than the muon precession frequency.