Permutation-Symmetric Multicritical Points in Random Antiferromagnetic Spin Chains

TL;DR

This paper develops a theoretical framework for multicritical points in random antiferromagnetic spin chains, revealing emergent symmetries at criticality and providing an analytic description of the quantum critical point in a spin-3/2 chain.

Contribution

It introduces a new class of multicritical points with enhanced symmetries in disordered spin chains and offers an analytic theory for the quantum critical point in the spin-3/2 case.

Findings

Identifies permutation-symmetric multicritical points in random spin chains

Provides an analytic description of the quantum critical point in spin-3/2 chains

Shows emergent symmetries at criticality

Abstract

The low-energy properties of a system at a critical point may have additional symmetries not present in the microscopic Hamiltonian. This letter presents the theory of a class of multicritical points that provide an interesting example of this in the phase diagrams of random antiferromagnetic spin chains. One case provides an analytic theory of the quantum critical point in the random spin-3/2 chain, studied in recent work by Refael, Kehrein and Fisher (cond-mat/0111295).