| Abstract | We have performed neutron scattering and a.c. susceptibility chi_a.c. studies on polycrystallline Tb_2Ti_2O_7 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 sim100 �, 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. |
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