  The nature of the low temperature ground state of the pyrochlore compound
Tb2Ti2O7 remains a puzzling issue. Dynamic fluctuations and short-range
correlations persist down to 50 mK, as evidenced by microscopic probes. In
parallel, magnetization measurements show irreversibilities and glassy behavior
below 200 mK. We have performed magnetization and AC susceptibility
measurements on four single crystals down to 57 mK. We did not observe a clear
plateau in the magnetization as a function of field along the [111] direction,
as suggested by the quantum spin ice model. In addition to a freezing around
200 mK, slow dynamics are observed in the AC susceptibility up to 4 K. The
overall frequency dependence cannot be described by a canonical spin-glass
behavior.
