Spin-wave lifetimes throughout the Brillouin zone.

S P Bayrakci, T Keller, K Habicht, B Keimer

文献索引：Science 312 , 1926-1929, (2006)

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摘要

We used a neutron spin-echo method with microelectron-volt resolution to determine the lifetimes of spin waves in the prototypical antiferromagnet MnF2 over the entire Brillouin zone. A theory based on the interaction of spin waves (magnons) with longitudinal spin fluctuations provides an excellent, parameter-free description of the data, except at the lowest momenta and temperatures. This is surprising, given the prominence of alternative theories based on magnon-magnon interactions in the literature. The results and technique open up a new avenue for the investigation of fundamental concepts in magnetism. The technique also allows measurement of the lifetimes of other elementary excitations, such as lattice vibrations, throughout the Brillouin zone.