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=265 mK. 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 quasielastic (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 , 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 265 mK, which we discuss in the context of recent mean field theoretical analysis.
©2011 American Physical Society
Copyright 2011 American Physical Society. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Physical Society