Impurity spin textures across conventional and deconfined quantum critical points of two-dimensional antiferromagnets

Abstract

We describe the spin distribution in the vicinity of a non-magnetic impurity in a two-dimensional antiferromagnet undergoing a transition from a magnetically ordered Neel state to a paramagnet with a spin gap. The quantum critical ground state in a finite system has total spin S=1/2 (if the system without the impurity had an even number of S=1/2 spins), and recent numerical studies in a double layer antiferromagnet (K. H.Hoglund et al., cond-mat/0611418) have shown that the spin has a universal spatial form delocalized across the entire sample. We present the field theory describing the uniform and staggered magnetizations in this spin texture for two classes of antiferromagnets: (i) the transition from a Neel state to a paramagnet with local spin singlets, in models with an even number of S=1/2 spins per unit cell, which are described by a O(3) Landau-Ginzburg-Wilson field theory; and (ii) the transition from a Neel state to a valence bond solid, in antiferromagnets with a single S=1/2 spin per unit cell, which are described by a deconfined field theory of spinons.

30 pages, 9 figures

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Cited by in corpus (8)

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• Strange metals and the AdS/CFT correspondence
• Incommensurate magnetic order and dynamics induced by spinless impurities in YBa${}_2$Cu${}_3$O${}_{6.6}$
• A maximally supersymmetric Kondo model
• Valence bond solid order near impurities in two-dimensional quantum antiferromagnets
• Impurity spin texture at a Néel-Valence Bond Solid critical point in $d=2$ SU(3) quantum antiferromagnets
• Site Dilution in the Half-Filled One-Band Hubbard Model: Ring Exchange, Charge Fluctuations and Application to La2Cu_{1-x}(Mg/Zn)_xO4
• Edge and impurity response in two-dimensional quantum antiferromagnets