First-order transition in the spin dynamics of geometrically frustrated Yb2Ti2O7.
Phys Rev Lett
; 88(7): 077204, 2002 Feb 18.
Article
em En
| MEDLINE
| ID: mdl-11863935
ABSTRACT
Using neutron diffraction, 170Yb Mössbauer and muon spin relaxation spectroscopies, we have examined the pyrochlore Yb2Ti2O7, where the Yb3+S' = 1/2 ground state has planar anisotropy. Below approximately 0.24 K, the temperature of the known specific-heat lambda transition, there is no long range magnetic order. We show that the transition corresponds to a first-order change in the fluctuation rate of the Yb3+ spins. Above the transition temperature, the rate, in the GHz range, follows a thermal excitation law, whereas below, the rate, in the MHz range, is temperature independent, indicative of a quantum fluctuation regime.
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Phys Rev Lett
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2002
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Article