Uncovering footprints of dipolar-octupolar quantum spin ice from neutron scattering signatures

TL;DR

This study investigates various quantum spin ice regimes in Ce$_2$Zr$_2$O$_7$, identifying the $ ext{pi}$-flux octupolar regime as most consistent with neutron scattering data, using exact diagonalization and molecular dynamics.

Contribution

It systematically analyzes all four quantum spin ice regimes in Ce$_2$Zr$_2$O$_7$ and identifies the $ ext{pi}$-flux octupolar regime as the most compatible with experimental observations.

Findings

Quantum structure factor matches neutron scattering data for the $ ext{pi}$-flux octupolar regime.

Distinct signatures differentiate quantum and classical spin ice regimes.

Quantum fluctuations significantly influence the spin structure factors.

Abstract

Recent experiments on Ce$_2$Zr$_2$O$_7$ suggest that this material may host a novel form of quantum spin ice, a three-dimensional quantum spin liquid with an emergent photon. The Ce$^{3+}$ local moments on the pyrochlore lattice are described by pseudospin 1/2 degrees of freedom, whose components transform as dipolar and octupolar moments under symmetry operations. In principle, there exist four possible quantum spin ice regimes, depending on whether the Ising component is in the dipolar/octupolar channel, and two possible flux configurations of the emergent gauge field. In this work, using exact diagonalization and molecular dynamics, we investigate the equal-time and dynamical spin structure factors in all four quantum spin ice regimes using quantum and classical computations. Contrasting the distinct signatures of quantum and classical results for the four possible quantum spin ice regimes and elucidating the role of quantum fluctuations, we show that the quantum structure factor computed for the $\pi$-flux octupolar quantum spin ice regime is most compatible with the neutron scattering results on Ce$_2$Zr$_2$O$_7$.