Two geometrically frustrated magnets studied by neutron diffraction

✍ Scribed by I. Mirebeau; A. Apetrei; I.N. Goncharenko; R. Moessner

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 407 KB
• Volume: 385-386
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2006.05.026

✦ Synopsis

In the pyrochlore compounds, Tb 2 Ti 2 O 7 and Tb 2 Sn 2 O 7 , only the Tb 3þ 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.