arXiv:2002.02543 · Annales Henri Poincaré
Dimerization and Néel Order in Different Quantum Spin Chains Through a Shared Loop Representation
Michael Aizenman, Hugo Duminil-Copin, Simone Warzel
Abstract
Abstract The ground-states of the spin-Santiferromagnetic chain $$H_{{\text {AF}}}$$ HAF with a projection-based interaction and the spin-1/2 XXZ-chain $$ H_{{\text {XXZ}}}$$ HXXZ at anisotropy parameter $$\Delta =\cosh (\lambda ) $$ Δ=cosh(λ) share a common loop representation in terms of a two-dimensional functional integral which is similar to the classical planarQ-state Potts model at $$ \sqrt{Q}= 2S+1 =2\cosh (\lambda )$$ Q=2S+1=2cosh(λ) . The multifaceted relation is used here to directly relate the distinct forms of translation symmetry breaking which are manifested in the ground-states of these two models: dimerization for $$H_{{\text {AF}}}$$ HAF at all $$S> 1/2$$ S>1/2 , and Néel order for $$ H_{{\text {XXZ}}} $$ HXXZ at $$\lambda >0$$ λ>0 . The results presented include: (i) a translation to the above quantum spin systems of the results which were recently proven by Duminil–Copin–Li–Manolescu for a broad class of two-dimensional random-cluster models, and (ii) a short proof of the symmetry breaking in a manner similar to the recent structural proof by Ray–Spinka of the discontinuity of the phase transition for $$Q>4$$ Q>4 . Altogether, the quantum manifestation of the change between $$Q=4$$ Q=4 and $$Q>4$$ Q>4 is a transition from a gapless ground-state to a pair of gapped and extensively distinct ground-states.