Mirebeau, I. and Goncharenko, I.N. and Cadavez-Peres, P. and Bramwell, S.T. and Gingras, M.J.P. and Gardner, J.S. (2002) Pressure-induced crystallization of a spin liquid. Nature , 420 (6911) pp. 54-57. 10.1038/nature01157.
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Liquids are expected to crystallize at low temperature. The only exception is helium, which can remain liquid at 0 K, owing to quantum fluctuations1, 2. Similarly, the atomic magnetic moments (spins) in a magnet are expected to order at a temperature scale set by the Curie–Weiss temperature thetaCW (ref. 3). Geometrically frustrated magnets represent an exception. In these systems, the pairwise spin interactions cannot be simultaneously minimized because of the lattice symmetry4. This can stabilize a liquid-like state of short-range-ordered fluctuating moments well below thetaCW (refs 5–7). Here we use neutron scattering to observe the spin liquid state in a geometrically frustrated system, Tb2Ti2O7, under conditions of high pressure (approx9 GPa) and low temperature (approx1 K). This compound is a three-dimensional magnet with thetaCW = -19 K, where the negative value indicates antiferromagnetic interactions. At ambient pressure Tb2Ti2O7 remains in a spin liquid state down to at least 70 mK (ref. 8). But we find that, under high pressure, the spins start to order or 'crystallize' below 2.1 K, with antiferromagnetic order coexisting with liquid-like fluctuations. These results indicate that a spin liquid/solid mixture can be induced by pressure in geometrically frustrated systems.
|Title:||Pressure-induced crystallization of a spin liquid|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Physics and Astronomy|
UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry
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