Speaker
Description
Rare-earth iron garnets constitute a model system for Néel ferrimagnetism. These materials exhibit temperature-dependent orbital cancellation of the magnetism associated with the electron spins, leaving a dense ensemble of polarized electrons which are of interest as a source for exotic spin-dependent fifth-force searches. We have conducted two novel investigations of a ferrimagnetic terbium iron garnet (Tb$_{3}$Fe$_{5}$O$_{12}$) sample: one using neutron spin echo spectroscopy, the other using neutron radiography. In contrast to measurements of external fields, neutrons can probe the internal state of the ferrimagnet and determine if the cancellation of moments occurs at the unit cell level or is an emergent property as a result of compensation among inhomogeneously-distributed domains. The use of polarized neutrons in both of these techniques enabled a search for exotic interactions between the polarized electrons in the sample and incident neutrons. We describe the sample characterization, the apparatus used, as well as preliminary results.
