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Two geometrically frustrated magnets studied by neutron diffraction

I. Mirebeau·A. Apetrei·I. N. Goncharenko·R. Moessner
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Abstract

In the pyrochlore compounds, Tb$_2$Ti$_2$O$_7$ and Tb$_2$Sn$_2$O$_7$, only the Tb$^{3+}$ ions are magnetic. They exhibit quite abnormal -- and, in view of their chemical similarity, strikingly different -- magnetic behaviour, as probed by neutron diffraction at ambient and applied pressure. Tb$_2$Ti$_2$O$_7$ is a cooperative paramagnet (`spin liquid'), without long range order at ambient pressure; however, it does become ordered under pressure. By contrast, Tb$_2$Sn$_2$O$_7$ enters an "ordered spin ice" state already at ambient pressure. We analyse a simple model which already clearly exhibits some of the qualitative features observed experimentally. Overall, comparing these two compounds emphasizes the power of small perturbations in selecting low-temperature states in geometrically frustrated systems.

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I. Mirebeau, A. Apetrei, I. N. Goncharenko, R. Moessner. 2006-02-16. Two geometrically frustrated magnets studied by neutron diffraction. https://doi.org/10.1016/j.physb.2006.05.026

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