Random SU(2)-symmetric spin-$S$ chains

Abstract

We study the low-energy physics of a broad class of time-reversal invariant and SU(2)-symmetric one-dimensional spin-S systems in the presence of quenched disorder via a strong-disorder renormalization-group technique. We show that, in general, there is an antiferromagnetic phase with an emergent SU(2S+1) symmetry. The ground state of this phase is a random singlet state in which the singlets are formed by pairs of spins. For integer spins, there is an additional antiferromagnetic phase which does not exhibit any emergent symmetry (except for S=1). The corresponding ground state is a random singlet one but the singlets are formed mostly by trios of spins. In each case the corresponding low-energy dynamics is activated, i.e., with a formally infinite dynamical exponent, and related to distinct infinite-randomness fixed points. The phase diagram has two other phases with ferromagnetic tendencies: a disordered ferromagnetic phase and a large spin phase in which the effective disorder is asymptotically finite. In the latter case, the dynamical scaling is governed by a conventional power law with a finite dynamical exponent.

32 pages, 11 figures; published version

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Cited by in corpus (7)

• Strong Disorder RG approach - a short review of recent developments
• Highly-symmetric random one-dimensional spin models
• Random free-fermion quantum spin chain with multi-spin interactions
• The case of SU$(3)$ criticality in spin-2 chains
• Emergent SU(N) symmetry in disordered SO(N) spin chains
• Signatures of infinite randomness in transport properties of disordered spin chains
• Critical behavior of dirty parafermionic chains