Abstract
We present results of Na23 and F19 nuclear magnetic resonance (NMR) measurements on NaCaCo2F7, a frustrated pyrochlore magnet with a Curie-Weiss temperature ΘCW≈-140 K and intrinsic bond disorder. Below 3.6 K both the Na23 and F19 spectra broaden substantially in comparison to higher temperatures accompanied by a considerable reduction (80%) of the NMR signal intensity: This proves a broad quasistatic field distribution. The F19 spin-lattice relaxation rate 19(1/T1) exhibits a peak at 2.9 K already starting to develop below 10 K. We attribute the spin freezing to the presence of bond disorder. This is corroborated by large-scale Monte Carlo simulations of a classical bond-disordered XY model on the pyrochlore lattice. The low freezing temperature, together with the very short magnetic correlation length not captured by the simulations, suggests that quantum effects play a decisive role in NaCaCo2F7.
Original language | English (US) |
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Article number | 235117 |
Journal | Physical Review B |
Volume | 96 |
Issue number | 23 |
DOIs | |
State | Published - Dec 12 2017 |
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics