Sprecher
Beschreibung
The measurement of the magnetic dynamical properties of strongly correlated frustrated spin-liquids presents a significant challenge for neutron scattering instrumentation. Spin-liquids can commonly present spin-fluctuations over a massive dynamical range, strongly correlated in Q-space. In addition, quantum spin-liquid candidate materials have low moments (spin-1/2 or 1) and therefore require high flux instrumentation to perform successful measurements.
Recently, Ramirez and co-workers [1,2] have pointed out the importance of the spin-glass transition in many quantum-spin-liquid materials, which counterintuitively, seems to be strongest in the limit of disorder-free samples. This underlines the importance of measuring spin-liquid materials with a wide energy range to cover the, often, high energy quantum spin-dynamics at low temperatures, and also to measure with high energy resolution to look for possible spin-freezing.
The quantum spin-liquid candidate material, ZnV2O4, contains just such a freezing transition in a sample which we have confirmed to be free of substitutional or occupational disorder and also free of lattice strain. We have used time-of-flight spectroscopy at both ISIS (MERLIN and LET) and the ILL (Panther) to examine the magnetic dynamical properties of ZnV2O4 with resolutions down to 30 μeV and dynamic ranges up to 50 meV at |Q| ~ 1.5 Å-1. ZnV2O4 exhibits complex, and highly correlated spin-dynamics over all energy scales measured, with a residual spin-dynamical spectral width of ~7 meV at the lowest temperatures - therefore due to quantum (non-thermally activated) fluctuations. The spin-glass freezing temperature is associated with only a fraction of the full magnetic spectral weight and is easily distinguished from temperature independent high-energy fluctuations. Our work highlights the importance of using a suite of instruments with various characteristics in order to get the full picture of the magnetic dynamics.
- Syzranov and Ramirez, Nat. Comms. (2022) 13:2993
- Syzranov, Phys. Rev. B 106 L140202 (2022)
