Unusual field dependence of spin fluctuations on different timescales in Tb2Ti2O7

We have investigated the spin dynamics of Tb2Ti2O7 as a function of magnetic field applied along the [111] axis using ac susceptibilty and muon-spin relaxation measurements. We find a significant increase in the imaginary part of the magnetic susceptibility at low fields at our lowest investigated temperature and an increased muon-spin relaxation rate in the same field range persisting to higher temperature. Comparing the data from the two techniques we identify three field regions where the dynamic properties of Tb2Ti2O7 appear to be evolving in different ways with crossovers between the regions at B1=15 and B2∼60 mT