Our latest paper has just been published in Physical Review Letters! In this paper, we find that LiYbO2 is the first experimental realisation of a spiral spin liquid ground state in an elongated diamond lattice. This work is significant as it overcomes previous experimental challenges in observing spiral spin liquids and combines magnetic Bragg and diffuse features in state-of-the-art RMC SPINVERT analysis.
Spiral spin liquids are relatively uncommon magnetic ground state, composed of a macroscopically degenerate manifold of fluctuating spin spirals that form closed contours or surfaces in reciprocal space. Materials with diamond lattices – such as those found in cubic spinels – have been theorised to host this novel spiral spin liquid ground state. However, many cubic spinels distort away from the perfect diamond structure, meaning that the spiral spin liquid is not realised. A recent re-imagining of the theory suggested it was still possible to realise this phase under a tetragonal elongation to the diamond lattice, but attempts at observing the spiral spin liquid have so far not been successful.
Our work, led by Jen, has involved comprehensive neutron diffraction measurements on WISH (ISIS) and D7 and D2B (ILL). We were able to verify from both an average and local structure perspective the spiral spin liquid ground state in LiYbO2, from its onset below 1.1 K. We modelled our D7 data using state-of-the-art SPINVERT analysis, and in doing so were able to reconstruct the smoking gun experimental signature, a broad continuous ring of scattering in reciprocal space (shown in c).