K. A. Ross, L. R. Yaraskavitch, M. Laver, J. S. Gardner, J. A. Quilliam, S. Meng, J. B. Kycia, D. K. Singh, H. A. Dabkowska, B. D. Gaulin
The pyrochlore material Yb2Ti2O7 displays unexpected quasi-two-dimensional
(2D) magnetic correlations within a cubic lattice environment at low
temperatures, before entering an exotic disordered ground state below T=265mK.
We report neutron scattering measurements of the thermal evolution of the 2D
spin correlations in space and time. Short range three dimensional (3D) spin
correlations develop below 400 mK, accompanied by a suppression in the
quasi-elastic (QE) scattering below ~ 0.2 meV. These show a slowly fluctuating
ground state with spins correlated over short distances within a
kagome-triangular-kagome (KTK) stack along [111], which evolves to isolated
kagome spin-stars at higher temperatures. Furthermore, low-temperature specific
heat results indicate a sample dependence to the putative transition
temperature that is bounded by 265mK, which we discuss in the context of recent
mean field theoretical analysis.
View original:
http://arxiv.org/abs/1107.2377
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