Single-ion magnon bound states in an antiferromagnet with strong uniaxial anisotropy

Katsumata, Kenji; Yamaguchi, Hideki; Hagiwara, Masayuki; Tokunaga, Masashi; Mikeska, H. J.; Goy, P.; Gross, Mark

doi:10.1103/physrevb.61.11632

Cited by 13 publications

(5 citation statements)

References 27 publications

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“…The same approach can also be applied to quasi-two-dimensional frustrated magnets [49]. So far multi-magnon bound states have been observed mostly in quasi-one-dimensional compounds but with different experimental techniques, such as absorption spectroscopy [6-12, 15, 17], inelastic neutron scattering [18,21] and electron spin resonance [13,14,16,19,20,22,23]. The same spectroscopic measurements can be used here to observe the emergent Efimov states of magnons, provided that the conservation of the magnetization along the magnetic field axis is weakly violated [8,9,20].…”

Section: Towards Experimental Realizationmentioning

confidence: 99%

“…We will also propose several approaches to experimentally realize the Efimov effect in quantum magnets, including frustrated cases. So far multi-magnon bound states have been observed with different experimental techniques, but mostly in quasi-one-dimensional compounds [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Although the Efimov effect emerges only in three dimensions [3,4], the same spectroscopic measurements can be used to observe the emergent Efimov states of magnons.…”

Section: Introductionmentioning

confidence: 99%

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Efimov effect in quantum magnets

Nishida

2012

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Physics is said to be universal when it emerges regardless of the underlying microscopic details. A prominent example is the Efimov effect, which predicts the emergence of an infinite tower of threebody bound states obeying discrete scale invariance when the particles interact resonantly. Because of its universality and peculiarity, the Efimov effect has been the subject of extensive research in chemical, atomic, nuclear and particle physics for decades. Here we employ an anisotropic Heisenberg model to show that collective excitations in quantum magnets (magnons) also exhibit the Efimov effect. We locate anisotropy-induced two-magnon resonances, compute binding energies of three magnons and find that they fit into the universal scaling law. We propose several approaches to experimentally realize the Efimov effect in quantum magnets, where the emergent Efimov states of magnons can be observed with commonly used spectroscopic measurements. Our study thus opens up new avenues for universal few-body physics in condensed matter systems.

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Section: Towards Experimental Realizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Efimov effect in quantum magnets

Nishida

2012

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“…The steep field-slope of several branches is clear evidence for their multi-magnon character, as discussed further below. Earlier far-infrared spectroscopy and electron spin resonance studies [22,23] observed the zero-field absorption branches at ν = 0.65, 0.88 and 0.97 THz. The high energy and field resolution of our experiments uncover new and very steep branches, as well as additional details that are important to fully understand the lowenergy excitations of FeI 2 (see Supplemental Information for comparison to earlier results).…”

Section: Methodsmentioning

confidence: 89%

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

Legros,

Zhang,

Bai

et al. 2020

Preprint

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“…∈ N is the particle number. Such measurements were performed on FeI 2 by means of infrared absorption [153,154], neutron scattering [155], and electron spin resonance [156]. However, with coupling, spin sectors mix and ∆S n (k) can assume any value, as recently seen in FeI 2 by terahertz spectroscopy [51].…”

Section: Spectroscopymentioning

confidence: 99%

Topological Hybrids of Magnons and Magnon Bound Pairs

Mook¹,

Hoyer²,

Klinovaja³

et al. 2022

Preprint

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We consider quantum condensed matter systems without particle-number conservation. Since the particle number is not a good quantum number, states belonging to different particle-number sectors can hybridize, which causes topological anticrossings in the spectrum. The resulting spectral gaps support chiral edge excitations whose wavefunction is a superposition of states in the two hybridized sectors. This situation is realized in fully saturated spin-anisotropic quantum magnets without spin conservation, in which single magnons hybridize with magnon bound pairs, i.e., two-magnon bound states. The resulting chiral edge excitations are exotic composites that carry mixed spin-multipolar character, inheriting spin-dipolar and spin-quadrupolar character from their single-particleness and two-particleness, respectively. In contrast to established topological magnons, the topological effects discussed here are of genuine quantum mechanical origin and vanish in the classical limit. We discuss implications for both intrinsic anomalous Hall-type transport and beyond-spintronics computation paradigms. We conclude that fully polarized quantum magnets are a promising platform for topology caused by hybridizations between particle-number sectors, complementing the field of ultracold atoms working with a conserved number of particles.

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Single-ion magnon bound states in an antiferromagnet with strong uniaxial anisotropy

Cited by 13 publications

References 27 publications

Efimov effect in quantum magnets

Efimov effect in quantum magnets

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

Topological Hybrids of Magnons and Magnon Bound Pairs

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