The pyrochlore system Yb2Ti2O7 has attracted both experimental and theoretical interest as a model geometrically frustrated magnet with large quantum fluctuations. These studies have identified two possible ground states for the material, where the state formed is dependent on the individual sample, and its pressure. This suggests that low-level structural disorder could be causing the change in ground state preference.
By using neutron scattering on SXD, which is very sensitive to the vacancies and displacements of oxygen ions, the researchers were able to determine the structure of the defects in single crystals of Yb2Ti2O7. They found that isolated oxygen vacancies on the O(2) site stabilise the formation of the spin liquid ground state, whereas ideal defect-free samples exhibit long-range order, with a ferromagnetic ground state.
Understanding the impact of these defects on the functionality of the pyrochlore system, and the competition between classically ordered systems and quantum states, could enable to development of novel quantum spin liquid phases.
Instrument: SXD, Merlin
Related publication: “Role of defects in determining the magnetic ground state of ytterbium titanate.” Nat Commun 10, 637 (2019)
Authors: DF Bowman (Royal Holloway, University of London), E Cemal (Royal Holloway, University of London, ILL), T Lehner (Royal Holloway, University of London), AR Wildes, L Mangin-Thro (ILL), GJ Nilsen (ILL, ISIS), MJ Gutmann, DJ Voneshen (ISIS), D Prabhakaran, AT Boothroyd (University of Oxford), DG Porter (Diamond Light Source), C Castelnovo (University of Cambridge), K Refson, JP Goff (Royal Holloway, University of London)