Article abstract
Nature Physics 3, 790 - 795 (2007)
Published online: 14 October 2007 | doi:10.1038/nphys749
Subject Categories: Condensed-matter physics | Materials physics
Spinons and triplons in spatially anisotropic frustrated antiferromagnets
Masanori Kohno1,2, Oleg A. Starykh3 & Leon Balents1
Abstract
The search for elementary excitations with fractional quantum numbers is a central challenge in modern condensed-matter physics. It has long been speculated that two-dimensional frustrated magnets might support quantum disordered states with neutral spin-1/2 excitations known as spinons. Despite decades of search, however, no clear experimental examples have been found. We explore the possibility for several materials using a realistic model, the spin-1/2 spatially anisotropic frustrated Heisenberg antiferromagnet in two dimensions. Here, we derive an effective Schrödinger equation valid in the weak interchain coupling regime. The dynamical spin correlations from this approach agree quantitatively without fitting parameters with inelastic neutron measurements of the triangular antiferromagnet Cs2CuCl4. In such antiferromagnets, the spectrum is composed of an incoherent continuum arising from the effects of one-dimensional spinons of individual chains, and a sharp dispersing peak, due to coherently propagating 'triplon' bound states of two spinons. We argue that triplons are generic features of spatially anisotropic frustrated antiferromagnets, which arise because the bound spinon pair lowers its kinetic energy by propagating between chains.
- Department of Physics, University of California, Santa Barbara, California 93106, USA
- Computational Materials Science Center, National Institute for Materials Science, Tsukuba 305-0047, Japan
- Department of Physics, University of Utah, Salt Lake City, Utah 84112, USA
Correspondence to: Leon Balents1 e-mail: balents@physics.ucsb.edu
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