Neutron scattering and a.c. susceptibility studies on the geometrically frustrated Tb₂Ti₂O₇

We have performed neutron scattering and a.c. susceptibility X_a.c. studies on polycrystallline Tb₂Ti₂O₇ to investigate the magnetic correlations in this antiferromagnetic pyrochlores. Evidence of changes in the magnetic correlation length has been observed by neutron diffraction in different parts of an applied field/temperature phase diagram. This cooperative paramagnet has been shown to increase its magnetic correlations, from nearest neighbour to ∼100 Å, in modest fields (<7 T) and temperatures (T > 2 K); however, in zero field the system does not order above 15 mK, even with its large moment.