Observation of 4- and 6-magnon bound-states in the spin-anisotropic frustrated antiferromagnet FeI$_2$

Legros, Anaëlle; Zhang, Shang-Shun; Bai, Xiaojian; Zhang, Hao; Dun, Zhiling; Phelan, W. Adam; Batista, Cristian D.; Mourigal, Martin; Armitage, N. P.

doi:10.48550/arxiv.2012.04205

Cited by 2 publications

(3 citation statements)

References 17 publications

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“…More details are in the text. been seen in FeI 2 both in neutron [29] and terahertz optics experiments [30]. These findings suggest the importance of magnon-magnon interactions that arise from anisotropic terms in the Hamiltonian, which are consequences of spin-orbit coupling.…”

Section: Introductionmentioning

confidence: 81%

Multimagnon dynamics and thermalization in the $S=1$ easy-axis ferromagnetic chain

Sharma,

Lee,

Changlani

2021

Preprint

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Quasiparticles are physically motivated mathematical constructs for simplifying the seemingly complicated many-body description of solids. A complete understanding of their dynamics and the nature of the effective interactions between them provides rich information on real material properties at the microscopic level. In this work, we explore the dynamics and interactions of magnon quasiparticles in a ferromagnetic spin-1 Heisenberg chain with easy-axis onsite anisotropy, a model relevant for the explanation of recent terahertz optics experiments on NiNb2O6 [P. Chauhan et al., Phys. Rev. Lett. 124, 037203 (2020)], and nonequilibrium dynamics in ultra cold atomic settings [W.C. Chung et al., Phys. Rev. Lett. 126, 163203 (2021)]. We build a picture for the properties of clouds of few magnons with the help of exact diagonalization and density matrix renormalization group calculations supported by physically motivated Jastrow wavefunctions. We show how the binding energy of magnons effectively reduces with their number and explain how this energy scale is of direct relevance for dynamical magnetic susceptibility measurements. This understanding is used to make predictions for ultra coldatomic platforms which are ideally suited to study the thermalization of multimagnon states. We simulate the nonequilibrium dynamics of these chains using the matrix product state based time-evolution block decimation algorithm and explore the dependence of revivals and thermalization on magnon density and easy-axis onsite anisotropy (which controls the strength of effective magnon interactions). We observe behaviors akin to those reported for many-body quantum scars which we explain with an analytic approximation that is accurate in the limit of small anisotropy.

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Section: Introductionmentioning

confidence: 81%

Multimagnon dynamics and thermalization in the $S=1$ easy-axis ferromagnetic chain

Sharma,

Lee,

Changlani

2021

Preprint

View full text Add to dashboard Cite

show abstract

“…Early neutron spectroscopy experiments (29) in the AF phase of FeI 2 elucidated that single-ion bound-states, previously identified by infrared spectroscopy (30), form quasiflat bands that lie below single-magnon excitations throughout the Brillouin zone. Our recent quantitative studies (24,31), have demonstrated that off-diagonal components of the nearest-neighbor exchange interaction are responsible for a high degree of hybridization between overlapping single-magnon excitations and heavy single-ion bound-states. These interactions can be parametrized using the spin-non-conserving terms S z i S + j and S + i S + j of energy scale J z± ≈ 1.1J 1 and J ±± ≈ 0.7J 1 , respectively, or using an extended Kitaev-Heisenberg model (32).…”

Section: Main Textmentioning

confidence: 99%

“…Further evidence for strong magnon interactions in FeI 2 comes from the observation of four-magnon and six-magnon bound-states in magneto-optics (31). These higher-order exchange bound-states are stabilized by the narrow-band of the system and the presence of ferromagnetic interactions at short distances.…”

Section: Main Textmentioning

confidence: 99%