Dimensional Evolution of Spin Correlations in the Magnetic Pyrochlore Yb2Ti2O7

TL;DR

This study investigates the evolution of spin correlations in Yb2Ti2O7, revealing a transition from quasi-2D to 3D correlations and a disordered ground state below 265mK, through neutron scattering and specific heat measurements.

Contribution

It provides detailed experimental insights into the temperature-dependent spin correlations and their dimensional evolution in Yb2Ti2O7, connecting to theoretical models.

Findings

Quasi-2D correlations exist at low temperatures.

3D correlations develop below 400 mK.

Disordered ground state below 265 mK.

Abstract

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.