Quantum Spin Fragmentation in Kagome Ice Ho3Mg2Sb3O14

TL;DR

This paper demonstrates that Ho3Mg2Sb3O14 exhibits a quantum spin-fragmented state on the kagome lattice, combining geometrical frustration with intrinsic quantum tunneling effects, leading to unique magnetic properties.

Contribution

It introduces Ho3Mg2Sb3O14 as a realization of a frustrated transverse Ising model with spin fragmentation and quantum dynamics driven by an intrinsic transverse field.

Findings

Observation of a symmetry-breaking transition at T*~0.32 K

Detection of a continuous magnetic excitation spectrum down to 0.12 K

Identification of a spin-fragmented state with quantum fluctuations

Abstract

A promising route to realize entangled magnetic states combines geometrical frustration with quantum-tunneling effects. Spin-ice materials are canonical examples of frustration, and Ising spins in a transverse magnetic field are the simplest many-body model of quantum tunneling. Here, we show that the tripod kagome lattice material Ho3Mg2Sb3O14 unites an ice-like magnetic degeneracy with quantum-tunneling terms generated by an intrinsic splitting of the Ho3+ ground-state doublet, realizing a frustrated transverse Ising model. Using neutron scattering and thermodynamic experiments, we observe a symmetry-breaking transition at T*~0.32 K to a remarkable quantum state with three peculiarities: a continuous magnetic excitation spectrum down to T~0.12K; a macroscopic degeneracy of ice-like states; and a fragmentation of the spin into periodic and aperiodic components strongly affected by quantum fluctuations. Our results establish that Ho3Mg2Sb3O14 realizes a spin-fragmented state on the kagome lattice, with intrinsic quantum dynamics generated by a homogeneous transverse field.