Hunting a [111] magnetization plateau to test the quantum spin ice model in Tb2Ti2O7

The pyrochlore magnet Tb2Ti2O7 may be described by a quantum spin ice model. This model predicts a magnetization plateau will occur for weak fields applied along the [111] axis at low-temperature. We have carried out muon-spin relaxation measurements to test this hypothesis. Features are observed at 15 and 65mT, agreeing with the predicted boundaries of the magnetization plateau. In the intermediate region the field dependence of the muon relaxation rate suggests a constant distribution of local magnetic fields of 10mT, and a constant fluctuation time of 20ns. ac susceptibility measurements are being carried out to investigate the bulk response on a longer timescale.