Tunneling-induced restoration of classical degeneracy in quantum kagome ice

Wu, Kai-Hsin; Huang, Yong‐Qing; Kao, Ying-Jer

doi:10.1103/physrevb.99.134440

Cited by 6 publications

(7 citation statements)

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“…Our results motivate further theoretical investigations of the effect of quantum fluctuations on partially ordered states, such as the spin fragmentation observed here for Ho 3 Mg 2 Sb 3 O 14 . The presence of long-range dipolar interactions and intrinsic transverse field further enriches the problem compared to quantum kagome Ising models studied previously [11,35,36,46,48]. Our ED calculations on small clusters suggest that the transverse field generates ring-flip tunneling processes that connect degenerate CSF configurations.…”

Section: Discussionmentioning

confidence: 52%

“…We use neutron-scattering experiments to determine this Hamiltonian, and employ a combination of exact diagonalization (ED), field theoretic, and Monte Carlo (MC) methods to understand its spin correlations and excitations. Our calculations complement previous studies of the quantum kagome ice model [11,35,36,46,48] by including dipolar interactions to delineate the putative role played by transverse fields to stabilize partially disordered quantum phases. In Ho 3 Mg 2 Sb 3 O 14 , however, the physics of Ho 3þ ions is profoundly affected by the strong nuclear hyperfine coupling, which eventually destroys coherent quantum effects between sites.…”

Section: Introductionmentioning

confidence: 54%

“…When the spins are confined to point either toward or away from the center of each triangle of the lattice, a highly degenerate kagome ice state is stabilized with a "one in, two out" or "two in, one out" local ice rule on each triangle [34]. Both a quantum-tunneling term and an external magnetic field are required to enable tunneling between these states [35,36]. Remarkably, when the longrange magnetic dipole-dipole interaction is introduced, the effective Coulomb interaction between emergent magnetic charges-defined in Fig.…”

Section: Introductionmentioning

confidence: 99%

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Quantum Versus Classical Spin Fragmentation in Dipolar Kagome Ice Ho3Mg2Sb3O<

et al. 2020

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A promising route to realize entangled magnetic states combines geometrical frustration with quantumtunneling 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 tripodkagome lattice material Ho 3 Mg 2 Sb 3 O 14 unites an icelike magnetic degeneracy with quantum-tunneling terms generated by an intrinsic splitting of the Ho 3þ ground-state doublet, which is further coupled to a nuclear spin bath. Using neutron scattering and thermodynamic experiments, we observe a symmetrybreaking transition at T Ã ≈ 0.32 K to a remarkable state with three peculiarities: a concurrent recovery of magnetic entropy associated with the strongly coupled electronic and nuclear degrees of freedom; a fragmentation of the spin into periodic and icelike components; and persistent inelastic magnetic excitations down to T ≈ 0.12 K. These observations deviate from expectations of classical spin fragmentation on a kagome lattice, but can be understood within a model of dipolar kagome ice under a homogeneous transverse magnetic field, which we survey with exact diagonalization on small clusters and mean-field calculations. In Ho 3 Mg 2 Sb 3 O 14 , hyperfine interactions dramatically alter the single-ion and collective properties, and suppress possible quantum correlations, rendering the fragmentation with predominantly single-ion quantum fluctuations. Our results highlight the crucial role played by hyperfine interactions in frustrated quantum magnets and motivate further investigations of the role of quantum fluctuations on partially ordered magnetic states.

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Section: Discussionmentioning

confidence: 52%

Section: Introductionmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

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Quantum Versus Classical Spin Fragmentation in Dipolar Kagome Ice Ho3Mg2Sb3O<

et al. 2020

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“…While the concepts presented so far are classical, the notion of fragmentation can be extended to quantum systems [22,[62][63][64], for example in relation to quantum kagome ice where a field-induced finite magnetisation may coexist with a ℤ 2 spin liquid [65][66][67][68]. Fragmentation can also occur via the decoupling of the equations of spin motions.…”

Section: Coexistence Of Order and Disordermentioning

confidence: 99%

Fragmentation in Frustrated Magnets: A Review

2020

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Spin liquids are exotic phases of matter that often support emergent gauge fields and quasi-particle excitations. While spin liquids are commonly known for remaining disordered, their definition has been extended to include phases with broken symmetry corresponding to (partial) long-range order, such as chiral and nematic spin liquids for example. For Coulomb spin liquids, this ordering can be quantitatively understood via a Helmholtz decomposition between divergence-free and divergencefull terms. This phenomenon has been coined fragmentation, where spin degrees of freedom fragment into two components: the fluctuating disordered part and the ordered one. In this review, we will cover the theoretical and experimental aspects of this growing field, in particular its relation to magnetic monopoles in spin ice, its phase diagram and the possibility to observe it in solid-state crystal and artificial networks.

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“…When the spins are confined to point either towards or away from the center of each triangle of the lattice, a highly degenerate kagome ice state is stabilized with a "one in, two out" or "two in, one out" local ice rule on each triangle [35]. Both a quantum-tunneling term and an external magnetic field are required to enable tunneling between these states [36,37]. Remarkably, when the long range magnetic dipole-dipole interaction is introduced, the effective Coulomb interaction between emergent magnetic charges-defined in Fig.…”

Section: Introductionmentioning

confidence: 99%

Quantum versus Classical Spin Fragmentation in Dipolar Kagome Ice Ho3Mg2Sb3O14

Dun,

Bai,

Paddison

et al. 2019

Preprint

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A promising route to realize entangled magnetic states combines geometrical frustration with quantumtunneling 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 Ho 3+ ground-state doublet, which is further coupled to a nuclear spin bath. 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 dramatic recovery of magnetic entropy associated with the strongly coupled electronic and nuclear degrees of freedom; a fragmentation of the spin into periodic and ice-like components strongly affected by quantum fluctuations; and persistent inelastic magnetic excitations down to T ≈ 0.12 K. These observations deviate from expectations of classical spin fragmentation physics on a kagome lattice, but can be understood within a framework of dipolar kagome ice under a homogeneous transverse magnetic field. By combining our experimental data with exact diagonalization and mean-field modeling, we establish the existence of a highly entangled fragmented state in a region where the transverse field remains a perturbation to the dipole-dipole interactions, which we coin as a quantum spin fragmented state. However, hyperfine interactions play a crucial role in suppressing quantum correlations and dramatically alter the single-ion and collective properties of Ho3Mg2Sb3O14. Our results highlight the crucial role played by hyperfine interactions in frustrated quantum magnets, and motivate further theoretical investigations of the interplay between spin fragmentation and coherent quantum tunneling.

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Tunneling-induced restoration of classical degeneracy in quantum kagome ice

Cited by 6 publications

References 54 publications

Quantum Versus Classical Spin Fragmentation in Dipolar Kagome Ice Ho3Mg2Sb3O<

Quantum Versus Classical Spin Fragmentation in Dipolar Kagome Ice Ho3Mg2Sb3O<

Fragmentation in Frustrated Magnets: A Review

Quantum versus Classical Spin Fragmentation in Dipolar Kagome Ice Ho3Mg2Sb3O14

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