Fractonic Constraints and Magnetic Order in a Dipole-Conserving Spin Chain

TL;DR

This paper studies a one-dimensional spin chain with dipole conservation and Ising interactions, revealing complex phase transitions and ordered states characterized by DMRG simulations and effective model mappings.

Contribution

It uncovers the phase diagram of a dipole-conserving spin chain with Ising interactions, highlighting novel dipole-ordered phases and phase transitions.

Findings

Dipole-ordered ground state stabilized despite kinetic constraints

Phase transition from dipole-ordered to spin antiferromagnetic phase at large Ising interactions

Existence of both antiferromagnetic and ferromagnetic dipole-ordered phases depending on interaction strength

Abstract

This work investigates the competition between dipole conservation, which imposes strong dynamical constraints and prevents the propagation of isolated spin excitations, and Ising-type interactions that favor ordering. Specifically, we explore the ground state phase diagram of a one-dimensional spin chain in the presence of both fractonic constraints and interactions. Despite the kinetic constraints, the system stabilizes an antiferromagnetic dipole-ordered ground state, where the ordering occurs at the level of spin pairs rather than individual spins. At a large Ising interaction strength, the model undergoes a phase transition from a dipole-ordered phase to a spin antiferromagnetic phase. In contrast, for ferromagnetic Ising interactions, the model exhibits both antiferromagnetic and ferromagnetic dipole ordered phases. At sufficiently large negative interaction strength, the dipole ordered phase transitions to a ferromagnetic phase with conventional spin ferromagnetic order. To characterize these distinct phases, we employ density matrix renormalization group (DMRG) simulations alongside large-scale diagonalization. We analyze appropriate order parameters, along with features of the entanglement spectrum and dynamical spectral functions. In limiting cases, the observed transitions can be understood by mapping the dipole conserving model onto effective XXZ models in a restricted Hilbert space of composite spins.