Spin Dynamics of the 2D Spin 12 Quantum Antiferromagnet Copper Deuteroformate Tetradeuterate (CFTD)
Henrik Moodysson Rønnow, MCMORROW Desmond Francis, R. Coldea +7 more
The magnetic excitation spectrum in the two-dimensional (2D) $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1/2$ Heisenberg antiferromagnet copper deuteroformate tetradeuterate has been measured for temperatures up to $T\ensuremath{\sim}J/2$, where $J\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}6.31\ifmmode\pm\else\textpm\fi{}0.02\mathrm{meV}$ is the 2D exchange coupling. For $T\ensuremath{\ll}J$, a dispersion of the zone boundary energy is observed, which is attributed to a wave vector dependent quantum renormalization. At higher temperatures, spin-wavelike excitations persist, but are found to broaden and soften. By combining our data with numerical calculations, and with existing theoretical work, a consistent description of the behavior of the model system is found over the whole temperature interval investigated.
Physical Review Letters•Jun 28, 2001•114 citations