Unravelling competing microscopic interactions at a phase boundary: A single-crystal study of the metastable antiferromagnetic pyrochlore 
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Sarkis, Colin; Rau, Jeffrey G.; Sanjeewa, Liurukara D.; Powell, Matthew; Kolis, Joseph W.; Marbey, Jonathan; Hill, Stephen; Rodríguez-Rivera, J. A.; Nair, Harikrishnan S.; Yahne, D. R.; Säubert, Steffen; Gingras, Michel J. P.; Ross, K. A.

doi:10.1103/physrevb.102.134418

Cited by 20 publications

(11 citation statements)

References 74 publications

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“…Since extended low energy modes are quite a common feature of frustrated magnets in general it seems likely that a similar framework may apply to several materials. In particular, given that a finite-temperature correlated phase is a feature of many Yb 3+ pyrochlores [49], the phenomenology seen here may prove generic to the entire class, particularly Yb 2 Ge 2 O 7 which also lies close to a phase boundary [50,51]. Moreover, since extended degenerate modes emerge on sev-eral phase boundaries of the pyrochlore anisotropic exchange model (Eq.…”

mentioning

confidence: 75%

Dynamical scaling as a signature of multiple phase competition in Yb$_2$Ti$_2$O$_7$

Scheie¹,

Benton²,

Taillefumier³

et al. 2022

Preprint

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Yb 2 Ti 2 O 7 is a celebrated example of a pyrochlore magnet with highly-frustrated, anisotropic exchange interactions. To date, attention has largely focused on its unusual, static properties, many of which can be understood as coming from the competition between different types of magnetic order. Here we use inelastic neutron scattering with exceptionally high energy resolution to explore the dynamical properties of Yb 2 Ti 2 O 7 . We find that spin correlations exhibit dynamical scaling, analogous to behaviour found near to a quantum critical point. We show that the observed scaling collapse can be explained within a phenomenological theory of multiple-phase competition, and confirm that a scaling collapse is also seen in semi-classical simulations of a microscopic model of Yb 2 Ti 2 O 7 . These results suggest a general picture for dynamics in systems with competing ground states.

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confidence: 75%

Dynamical scaling as a signature of multiple phase competition in Yb$_2$Ti$_2$O$_7$

Scheie¹,

Benton²,

Taillefumier³

et al. 2022

Preprint

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“…( 3) is already an important simplification of the most general multipolar Hamiltonian [2] one would expect for Tb 2 Ge 2 O 7 , even a somewhat accurate determination of "only" the five parameters {J zz , J ± , J z± , J ±± , λ} by fitting the experimental data would be a challenging task at the present time. To appreciate this, one may consider the significant theoretical and experimental efforts spanning nearly ten years that have been required to determine the equivalent of those couplings (whose projection in the crystal field ground doublet yield an effective pseudospin-1/2 model) for Yb 2 Ti 2 O 7 [104,105], Yb 2 Ge 2 O 7 [13] and Er 2 Ti 2 O 7 [16], and where the added complexities of lowlying excited crystal field levels (as is the case for terbium pyrochlores) does not exist [106]. In addition, such a procedure was only possible for those three compounds thanks to the availability of large high-quality single crystals.…”

Section: Open Questions and Conclusionmentioning

confidence: 99%

“…Rare earth pyrochlores have proven to be a preferred setting to explore the physics of magnetic phase competition [7]. This is epitomized by several XY pyrochlores [8][9][10][11][12][13][14], which * Email: alannah.hallas@ubc.ca appear fine-tuned to lie near the cusp of adjacent magnetically ordered states, inducing proximate quantum spin liquid behavior [1,2,15]. Most of this phase behavior has been successfully rationalized in the context of a nearest-neighbor Hamiltonian with anisotropic bilinear couplings between pseudospin S = 1 /2 degrees of freedom [8,[15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Intertwined Magnetic Dipolar and Electric Quadrupolar Correlations in the Pyrochlore Tb$_2$Ge$_2$O$_7$

Hallas,

Jin,

Gaudet

et al. 2020

Preprint

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We present a comprehensive experimental and theoretical study of the pyrochlore Tb 2 Ge 2 O 7 , an exemplary realization of a material whose properties are dominated by competition between magnetic dipolar and electric quadrupolar correlations. The dipolar and quadrupolar correlations evolve over three distinct regimes that we characterize via heat capacity, elastic and inelastic neutron scattering. In the first regime, above T * = 1.1 K, significant quadrupolar correlations lead to an intense inelastic mode that cannot be accounted for within a scenario with solely magnetic dipole-dipole correlations. The onset of extended dipole correlations occurs in the intermediate regime, between T * = 1.1 K and T c = 0.25 K, with the formation of a collective paramagnetic state characterized by extended ferromagnetic canted spin ice domains. Here, long-range order is impeded not only by the usual frustration operating in classical spin ice systems, but also by a competition between dipolar and quadrupolar correlations. Finally, in the lowest temperature regime, below T c = 0.25 K, there is an abrupt and significant increase in the dipole ordered moment. The majority of the ordered moment remains tied up in the ferromagnetic spin ice-like state, but an additional k = (0, 0, 1) antiferromagnetic order parameter also develops. Simultaneously, the spectral weight of the inelastic mode, which is a proxy for the quadrupolar correlations, is observed to drop, indicating that dipole order ultimately wins out. Tb 2 Ge 2 O 7 is therefore a remarkable platform to study intertwined dipolar and quadrupolar correlations in a magnetically frustrated system and provides important insights into the physics of the whole family of terbium pyrochlores.

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“…However, fits to CEF neutron scattering peaks can sometimes be underdetermined (c.f. Yb 2 Ge 2 O 7 [10,11]) and CEF-derived anisotropy does not always match bulk measures of anisotropy (c.f. YbCl 3 [12]).…”

Section: Introductionmentioning

confidence: 99%

Quantifying uncertainties in crystal electric field Hamiltonian fits to neutron data

Scheie

2022

SciPost Phys. Core

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We systematically examine uncertainties from fitting rare earth single-ion crystal electric field (CEF) Hamiltonians to inelastic neutron scattering data. Using pyrochlore and delafossite structures as test cases, we find that uncertainty in CEF parameters can be large despite visually excellent fits. These results show Yb^{3+}3+ compounds have particularly large gg-tensor uncertainty because of the few available peaks. In such cases, additional constraints are necessary for meaningful fits.

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Unravelling competing microscopic interactions at a phase boundary: A single-crystal study of the metastable antiferromagnetic pyrochlore Yb2Ge2O7

Cited by 20 publications

References 74 publications

Dynamical scaling as a signature of multiple phase competition in Yb$_2$Ti$_2$O$_7$

Dynamical scaling as a signature of multiple phase competition in Yb$_2$Ti$_2$O$_7$

Intertwined Magnetic Dipolar and Electric Quadrupolar Correlations in the Pyrochlore Tb$_2$Ge$_2$O$_7$

Quantifying uncertainties in crystal electric field Hamiltonian fits to neutron data

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