Extended Coulomb liquid of paired hardcore boson model on a pyrochlore lattice

Chun-Jiong Huang,Changle Liu,Youjin Deng,Yue Yu,Ziyang Meng,Gang Chen

doi:10.1103/physrevresearch.2.042022

Abstract

There is a growing interest in the $U(1)$ Coulomb liquid in both quantum materials in pyrochlore ice and cluster Mott insulators and cold atom systems. We explore a paired hardcore boson model on a pyrochlore lattice. This model is equivalent to the XYZ spin model that was proposed for rare-earth pyrochlores with "dipole-octupole" doublets. Since this model has no sign problem for quantum Monte Carlo (QMC) simulations in a large parameter regime, we carry out both analytical and QMC calculations. We find that the $U(1)$ Coulomb liquid is quite stable and spans a rather large portion of the phase diagram with boson pairing. Moreover, we numerically find thermodynamic evidence that the boson pairing could induce a possible $\mathbb{Z}_2$ liquid in the vicinity of the phase boundary between Coulomb liquid and $\mathbb{Z}_2$ symmetry-broken phase. Besides the materials' relevance with quantum spin ice, we point to quantum simulation with cold atoms on optical lattices.

Highlights

The search of exotic quantum phases with quantum number fractionalization and emergent gauge structure has been an active subject in modern condensed matter physics
When t1 and t2 are small, a U (1) Coulomb liquid is stable with emergent U (1) gauge structure
As for the physical realization, the solid-state realization has been proposed for dipole-octupole doublets that have a XYZ model interaction [7,8,38]

Summary

Rapid Communications

There is growing interest in the U (1) Coulomb liquid in both quantum materials in pyrochlore ice and cluster Mott insulators and cold-atom systems. We explore a paired hardcore boson model on a pyrochlore lattice. This model is equivalent to the XYZ spin model that was proposed for rare-earth-metal pyrochlores with “dipoleoctupole” doublets. Since our model has no sign problem for quantum Monte Carlo (QMC) simulations in a large parameter regime, we carry out both analytical and QMC calculations. We find that the U (1) Coulomb liquid is quite stable and spans a rather large portion of the phase diagram with boson pairing. Besides the materials’ relevance with quantum spin ice, we point to quantum simulation with cold atoms on optical lattices

Introduction

Published by the American Physical Society

Gapped Activated Expo decay Expo decay

Discussion