Cross-tunneling and phonon bottleneck effects in the relaxation phenomena of XY pyrochlore antiferromagnet Er2Ti2O7
2016
Abstract
A multiple time scale relaxation dynamic is revealed by alternating current (ac) susceptibility studies of a single crystal of Er2Ti2O7 performed at high temperatures (k(B)T >> J/k(B)) in a wide range of static magnetic fields. An analysis of the frequency dependence of the ac susceptibility revealed the existence of two relaxationmechanisms, identified as an Orbach process with the pronounced effect of a phonon bottleneck and cross-tunneling.
The origin of the phonon bottleneck is attributed to resonant phonon trapping. The relevance of the obtained results for relaxation phenomena found in other rare-earth pyrochlores, studied under similar conditions, is discussed.