Low-temperature thermal expansion behavior of the geometrically frustrated pyrochlore Tb2Ti2O7

The low-temperature lattice behavior of the pyrochlore magnet Tb2Ti2O7 has been investigated by thermal expansion measurements. The thermal expansion coefficient of Tb2Ti2O7 shows no anomaly except for a shoulder around 8 K, which can be explained by a Schottky type excitation arising from the energy gap between the ground-state and first excited CEF doublets. The analysis of the thermal expansion behavior combined with the heat capacity data indicates the lack of strong spin-lattice coupling in the thermal expansion at the low temperature region, where the spin liquid state emerges.