Dresden 2006 – wissenschaftliches Programm

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MA: Magnetismus

MA 27: Spin-Dynamics, Magnetization Reversal II

MA 27.4: Vortrag

Donnerstag, 30. März 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).