Abstract
We present the results of a combined -NMR and diffraction study on , a member of the “breathing” pyrochlore family. Via specific heat and NMR measurements, we find that the complex sequence of first-order transitions observed for is replaced by a single second-order transition at . Neutron and x-ray diffraction rule out both structural symmetry lowering and magnetic long-range order as the origin of this transition. Instead, reverse Monte Carlo fitting of the magnetic diffuse scattering indicates that the low-temperature phase may be described as a collinear spin nematic state, characterized by a quadrupolar order parameter. This state also shows signs of short-range order between collinear spin arrangements on tetrahedra, revealed by mapping the reverse Monte Carlo spin configurations onto a three-state color model.
- Received 16 February 2017
DOI:https://doi.org/10.1103/PhysRevLett.119.087201
© 2017 American Physical Society