2003/04/30 by W. Zwerger · 8 citations
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Physics of Superconductivity and Magnetism #Theoretical and Computational Physics #cond-mat.stat-mech #cond-mat.str-el
paper · pdf · doi:10.1103/physrevlett.92.027203
published as Physical Review Letters 92, 027203 (2004) · final version, minor changes
openalex publication_date 2004/01/16 · arxiv created 2004/01/26 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
It is shown that the Goldstone modes associated with a broken continuous symmetry lead to anomalously large fluctuations of the zero field order parameter at any temperature below T(c). In dimensions 2<d<4, the variance of the extensive spontaneous magnetization scales as L4 with the system size L, independent of the order parameter dynamics. The anomalous scaling is a consequence of the 1/q(4-d) divergence of the longitudinal susceptibility. For ground states in two dimensions with Goldstone modes vanishing linearly with momentum, the dynamical susceptibility contains a singular contribution (q(2)-omega(2)/c(2))(-1/2). The dynamic structure factor thus exhibits a critical continuum above the undamped spin wave pole, which may be detected by neutron scattering in the Néel phase of 2D quantum antiferromagnets.