Dresden 2006 – scientific programme
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MA: Magnetismus
MA 27: Spin-Dynamics, Magnetization Reversal II
MA 27.4: Talk
Thursday, March 30, 2006, 11:00–11:15, HSZ 403
Magnon decay in gapped quantum spin systems — •Oleksiy Kolezhuk and Subir Sachdev — Physics Dept., Harvard University, Cambridge MA 02138, USA
In the O(3) σ-model description of gapped spin systems, S=1 magnons can only decay into three lower energy magnons. We show that the symmetry of the quantum spin Hamiltonian often allows decay into two magnons, and compute this decay rate in model systems. It is argued that two-magnon decay is present in Haldane gap S=1 spin chains, even though it cannot be induced by any allowed term written in powers and gradients of the σ-model field. We compare our results with recent measurements of Stone et al. on a two-dimensional spin system (C4H12N2)Cu2Cl6 (known as PHCC).