Magnons and factons in diluted antiferromagnets (invited)

摘要: Site‐diluted antiferromagnets with short‐range interactions can serve as a model magnetic percolation system. A length scale ξ exists such that for scales (1/q)>ξ the structure is continuous (hydrodynamic limit), and excitations are antiferromagnetic magnons, stiffness constant which depends critically upon concentration. For (1/q)<ξ, fractal, fractons, characteristic dispersion law. The fracton (strongly) spatially localized. magnons expected to be extended in very long limit, possibility of Anderson (weak) localization longer than ξ. cross over from magnon at an energy ωc∝ξ−[1+(θ/2)], where θ anomalous diffusion exponent. We have calculated scattering form factor I(q,ω) d=3 simple cubic antiferromagnet within effective medium approximation (EMA), a...