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Hallas, Alannah; Gaudet, Jonathan; Wilson, M. N.; Munsie, Timothy; Aczel, A. A.; Stone, M. B.; Freitas, R. S.; Arévalo‐López, Ángel M.; Attfield, J. Paul; Tachibana, Makoto; Wiebe, C. R.; Luke, G. M.; Gaulin, B. D.

doi:10.1103/physrevb.93.104405

Cited by 38 publications

(38 citation statements)

References 60 publications

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“…while Yb 2 Ge 2 O 7 [90] shows Γ 5 antiferromagnetic order. However, both show a similar broad continuum of excitations [4,90] at zero-field. While a detailed parametrization of the exchange in Yb 2 Sn 2 O 7 or Yb 2 Ge 2 O 7 has not yet been carried out, it is plausible that they also live close to the SFM-Γ 5 phase boundary [31], like Yb 2 Ti 2 O 7 .…”

Section: Discussionmentioning

confidence: 99%

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Magnon interactions in the frustrated pyrochlore ferromagnet Yb2Ti2O7

2019

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The frustrated rare-earth pyrochlore Yb 2 Ti 2 O 7 is remarkable among magnetic materials: despite a ferromagnetically ordered ground state it exhibits a broad, nearly gapless, continuum of excitations. This broad continuum connects smoothly to the sharp one-magnon excitations expected, and indeed observed, at high magnetic fields, raising the question: how does this picture of sharp magnons break down as the field is lowered? In this paper, we consider the effects of magnon interactions in Yb 2 Ti 2 O 7 , showing that their inclusion greatly extends the reach of spin-wave theory. First, we show that magnon interactions shift the phase boundary between the (splayed) ferromagnet (SFM) and the antiferromagnetic Γ 5 phase so that Yb 2 Ti 2 O 7 lies very close to it. Next, we show how the high-field limit connects to lower fields; this includes corrections to the critical fields for the [111] and [110] directions, bringing them closer to the observed experimental values, as well as accounting for the departures from linear spin wave theory that appear in [001] applied fields below 3 T [Thompson et al., Phys. Rev. Lett. 119, 057203 (2017)]. Turning to low-fields, though the extent of the experimentally observed broadening is not quite reproduced, we find a rough correspondence between non-linear spin-wave theory and inelastic neutron scattering data on both a single-crystal sample, as well as on a powder sample [Peçanha-Antonio et al., Phys. Rev. B, 96, 214415 (2017)]. We conclude with an outlook on implications for future experimental and theoretical work on Yb 2 Ti 2 O 7 and related materials, highlighting the importance of proximity to the splayed ferromagnet-Γ 5 phase boundary and its potential role in intrinsic or extrinsic explanations of the low-field physics of Yb 2 Ti 2 O 7 .where ω = e 2πi/3 and the local axes, (x r ,ŷ r ,ẑ r ), follow the convention of Savary et al.[69] (see App. A).We primarily consider the parameters obtained in J zz = +0.026 meV, J ± = +0.074 meV, J ±± = +0.048 meV, J z± = −0.159 meV,

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Section: Discussionmentioning

confidence: 99%

“…One, Yb 2 Sn 2 O 7 , is known to have a SFM ground state [89]. while Yb 2 Ge 2 O 7 [90] shows Γ 5 antiferromagnetic order. However, both show a similar broad continuum of excitations [4,90] at zero-field.…”

Section: Discussionmentioning

confidence: 99%

Magnon interactions in the frustrated pyrochlore ferromagnet Yb2Ti2O7

2019

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“…The details of the high pressure synthetic method employed are given in Ref. [28] for the Er 2 Ge 2 O 7 sample and in Ref. [29] for the Er 2 Pt 2 O 7 sample.…”

Section: Methodsmentioning

confidence: 99%

Effect of chemical pressure on the crystal electric field states of erbium pyrochlore magnets

et al. 2018

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We have carried out a systematic study of the crystal electric field excitations in the family of cubic pyrochlores Er2B2O7, with B = Ge, Ti, Pt, and Sn, using neutron spectroscopy. All members of this family are magnetic insulators based on 4f11 Er 3+ and non-magnetic B 4+ . At sufficiently low temperatures, long-range antiferromagnetic order is observed in each of these Er2B2O7 pyrochlores. Our inelastic neutron scattering measurements probe the transitions from the ground state doublet to excited crystal electric field states belonging to the J = 15/2 Hund's rules manifold. This allows us to quantitatively determine the energy eigenvalues and eigenfunctions of these (2J + 1) = 16 states across the Er2B2O7 series. The different ionic sizes associated with different non-magnetic B 4+ cations correspond to positive or negative chemical pressure, depending on the relative contraction or expansion of the crystal lattice, which gives rise to different local environments at the Er 3+ site. Our results show that the g-tensor components are XY-like for all four members of the Er2B2O7 series. However, the XY anisotropy is much stronger for Er2Pt2O7 and Er2Sn2O7 ( g ⊥/g z > 25), than for Er2Ge2O7 and Er2Ti2O7 ( g ⊥/g z < 4). The variation in the nature of the XY-anisotropy in these systems correlates strongly with their ground states, as Er2Ge2O7 and Er2Ti2O7 order into Γ5 magnetic structures, while Er2Pt2O7 and Er2Sn2O7 order in the Γ7 Palmer-Chalker structure.

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“…We demonstrate that, depending on the field direction, a combination of two-, three-, and possibly six-fold Zeeman clock terms emerge and compete with the six-fold clock term present in zero field. We anticipate this work will help determine the ground state selection and field effects in other topical Γ 5 pyrochlores, such as NaCaCo 2 F 7 [29] [30,31].…”

Section: Discussionmentioning

confidence: 99%

Experimental evidence for field-induced emergent clock anisotropies in the XY pyrochlore Er2Ti2O7

et al. 2017

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The XY pyrochlore antiferromagnet Er2Ti2O7 exhibits a rare case of Z6 discrete symmetry breaking in its ψ2 magnetic ground state. Despite being well-studied theoretically, systems with high discrete symmetry breakings are uncommon in nature and, thus, Er2Ti2O7 provides an experimental playground for the study of broken Zn symmetry, for n > 2. A recent theoretical work examined the effect of a magnetic field on a pyrochlore lattice with broken Z6 symmetry and applied it to Er2Ti2O7. This study predicted multiple domain transitions depending on the crystallographic orientation of the magnetic field, inducing rich and controllable magnetothermodynamic behavior. In this work, we present neutron scattering measurements on Er2Ti2O7 with a magnetic field applied along the [001] and [111] directions, and provide the first experimental observation of these exotic domain transitions. In a [001] field, we observe a ψ2 to ψ3 transition at a critical field of 0.18 ± 0.05 T. We are thus able to extend the concept of the spin-flop transition, which has long been observed in Ising systems, to higher discrete Zn symmetries. In a [111] field, we observe a series of domain-based phase transitions for fields of 0.15 ± 0.03 T and 0.40 ± 0.03 T. We show that these field-induced transitions are consistent with the emergence of two-fold, three-fold and possibly six-fold Zeeman terms. Considering all the possible ψ2 and ψ3 domains, these Zeeman terms can be mapped onto an analog clock -exemplifying a literal clock anisotropy. Lastly, our quantitative analysis of the [001] domain transition in Er2Ti2O7 is consistent with order-by-disorder as the dominant ground state selection mechanism.

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XY antiferromagnetic ground state in the effectiveS=12pyrochloreYb2Ge2O7

Cited by 38 publications

References 60 publications

Magnon interactions in the frustrated pyrochlore ferromagnet Yb2Ti2O7

Magnon interactions in the frustrated pyrochlore ferromagnet Yb2Ti2O7

Effect of chemical pressure on the crystal electric field states of erbium pyrochlore magnets

Experimental evidence for field-induced emergent clock anisotropies in the XY pyrochlore Er2Ti2O7

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