Degenerate and chiral states in the extended Heisenberg model on the kagome lattice

Albarracín, F. A. Gómez; Pujol, Pierre

doi:10.1103/physrevb.97.104419

Cited by 17 publications

(12 citation statements)

References 35 publications

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“…This change is reflected in the χ nn1 curves: at low fields, χ nn1 = 0, corresponding to the single-q phase, and as the system is further magnetized, it enters in the double-q phase with a non-zero net chirality. Although the singleq phase has no net chirality, a closer look reveals that the spin arrangement has an alternate chirality, similar to what has been seen in kagome for example in the cuboc phases 36,37 . This is illustrated in Fig.…”

Section: Double-q and Single-q Phasessupporting

confidence: 60%

“…13 A), with the two types of plaquettes illustrated in the inset. The inspection of the sublattice snapshots reveals a particular form of semiextensive generacy, similar to that seen in the extended Heisenberg model in the kagome lattice 37 : two sublattices can exchange "lines" of spins, and this gives rise to the two types of umbrella plaquettes, which have opposite chirality. In panels B and D from Fig.…”

Section: Double-q and Single-q Phasessupporting

confidence: 55%

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Chiral multiple-q and skyrmion phases induced by Rashba-Hund interactions in the kagome lattice

Villalba¹,

Albarracín²,

Cabra³

et al. 2022

Preprint

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Engineering non trivial topological phases in materials, specially skyrmion-like arrangements, has been of great interest in the last decade due to its potential technological applications. In this work, we study a model of electrons coupled to a magnetic texture in the kagome lattice interacting with magnetic moments via Rashba spin orbit coupling in the large Hund interaction limit. We obtain the effective spin Hamiltonian and study the emergent low temperature phases under an external magnetic field using large scale Monte Carlo simulations. We show that strong geometric frustration, characteristic of the kagome lattice, and the competition between the effective exchange, antisymmetric and anisotropic couplings, gives rise to a large variety of non-trivial topological phases. On the one hand, for antiferromagnetic exchange coupling a pseudo-antiferromagnetic skyrmion crystal is stabilized for a broad range of parameters. As the exchange coupling gets smaller, chiral single-q and double-q phases emerge. On the other hand, in the ferromagnetic case, even though the competition of the different interactions produce a series of exotic textures, a remarkable parallel may be drawn with the pure ferromagnetic model with antisymmetric interactions. Finally, for the special case where the exchange coupling is completely suppressed, we show that, coming from a higher temperature cooperative paramagnet, an "umbrella-like" plaquette order with semiextensive degeneracy is induced by the external magnetic field.

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Section: Double-q and Single-q Phasessupporting

confidence: 60%

Section: Double-q and Single-q Phasessupporting

confidence: 55%

Chiral multiple-q and skyrmion phases induced by Rashba-Hund interactions in the kagome lattice

Villalba¹,

Albarracín²,

Cabra³

et al. 2022

Preprint

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“…11(a) and is referred to as cuboc 1 order (which appears in several contexts in kagome spin models [46]). Indeed, it has previously been realized that the line J 2 = J 3d < J 1 of the J 1 -J 2 -J 3d model as considered here, marks the phase boundary between = 0 and cuboc 1 ordered regimes [47][48][49][50]. The key question is whether defects with ∆E > 0 are local energy minima and how they are modified when performing iterative minimization as has been done for the defects in the XY-model (see Sec.…”

Section: Single Defects In the Heisenberg Modelsmentioning

confidence: 88%

“…Through a suitable inclusion of longer-range couplings, this degeneracy is lifted to become subextensive, hence, realizing an environment for fracton physics (see Refs. [46][47][48][49][50][51][52][53][54][55][56] for a selection of works about related kagome models with longer-range interactions). The ground and excited states may be most conveniently described by defect variables associated with local spin constraints.…”

Section: Introductionmentioning

confidence: 99%

Fracton excitations in classical frustrated kagome spin models

Hering,

Yan,

Reuther

2020

Preprint

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Fractons are topological quasiparticles with limited mobility. While there exists a variety of models hosting these excitations, typical fracton systems require rather complicated many-particle interactions. Here, we discuss fracton behavior in the more common physical setting of classical kagome spin models with frustrated two-body interactions only. We investigate systems with different types of elementary spin degrees of freedom (three-state Potts, XY, and Heisenberg spins) which all exhibit characteristic subsystem symmetries and fracton-like excitations. The mobility constraints of isolated fractons and bound fracton pairs in the three-state Potts model are, however, strikingly different compared to the known type-I or type-II fracton models. One may still explain these properties in terms of type-I fracton behavior and construct an effective low-energy tensor gauge theory when considering the system as a 2D cut of a 3D cubic lattice model. Our extensive classical Monte-Carlo simulations further indicate a crossover into a low temperature glassy phase where the system gets trapped in metastable fracton states. Moving on to XY spins, we find that in addition to fractons the system hosts fractional vortex excitations. As a result of the restricted mobility of both types of defects, our classical Monte-Carlo simulations do not indicate a Kosterlitz-Thouless transition but again show a crossover into a glassy low-temperature regime. Finally, the energy barriers associated with fractons vanish in the case of Heisenberg spins, such that defect states may continuously decay into a ground state. These decays, however, exhibit a power-law relaxation behavior which leads to slow equilibration dynamics at low temperatures.

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“…In the SO(3) invariant ∆ = 1 case, the classical T = 0 phase diagram of this model is well known: it presents the so called "cuboc" phases (with spontaneous and alternate scalar chirality), and a q = 0 phase 21,22 for J 3 < J 2 < J 1 . At the special line J 2 = J 3 < J 1 , the ground state has a semi-extensive degeneracy 21 where lines of spins from the q = 0 order can be "swapped". For practical reasons, we will take J 1 = 1 for the rest of the manuscript.…”

mentioning

confidence: 99%

Chiral phase transition and thermal Hall effect in an anisotropic spin model on the kagome lattice

Albarracín,

Rosales,

Pujol

2020

Preprint

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We present a study of the thermal Hall effect in the extended Heisenberg model with XXZ anisotropy in the kagome lattice. This model has the particularity that, in the classical case, and for a broad region in parameter space, an external magnetic field induces a chiral symmetry breaking: the ground state is a doubly degenerate q = 0 order with either positive or negative net chirality. Here, we focus on the effect of this chiral phase transition in the thermal Hall conductivity using Linear-Spin-Waves theory. We explore the topology and calculate the Chern numbers of the magnonic bands, obtaining a variety of topological phase transitions. We also compute the quantum corrections to the critical temperature associated with the chiral phase transition (T SW c ). Our main result is that, the thermal Hall conductivity, which is nul for T > T SW c , becomes non-zero as a consequence of the spontaneaous chiral symmetry breaking at low temperatures. Therefore, we present a simple model where it is possible to "switch" on/off the thermal transport properties introducing a magnetic field and heating or cooling the system.

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Degenerate and chiral states in the extended Heisenberg model on the kagome lattice

Cited by 17 publications

References 35 publications

Chiral multiple-q and skyrmion phases induced by Rashba-Hund interactions in the kagome lattice

Chiral multiple-q and skyrmion phases induced by Rashba-Hund interactions in the kagome lattice

Fracton excitations in classical frustrated kagome spin models

Chiral phase transition and thermal Hall effect in an anisotropic spin model on the kagome lattice

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