Evolution of the propagation vector of antiferroquadrupolar phases in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Ce</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi>Pd</mml:mi><mml:mn>20</mml:mn></mml:msub><mml:msub><mml:mi>Si</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:mrow></mml:math>under magnetic field

Portnichenko, P. Y.; Nikitin, S. E.; Prokofiev, A.; Paschen, S.; Mignot, J.-M.; Ollivier, Jacques; Podlesnyak, A.; Meng, Siqin; Lu, Zhilun; Inosov, D. S.

doi:10.1103/physrevb.99.214431

Cited by 6 publications

(7 citation statements)

References 52 publications

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“…Additional methods for characterizing HO are desirable. One way is to look at the magnetic excitation spectrum in the HO phase which carries the imprint of the multipolar interactions and the HO parameter in its dispersion relations [6,27]. In the conventional approach, the dispersion is calculated using a specific candidate model for the HO in some fixed applied field and then compared to the dynamical structure factor measured by single-crystal inelastic neutron scattering (INS).…”

Section: Introductionmentioning

confidence: 99%

Field-Angle-Resolved Magnetic Excitations as a Probe of Hidden-Order Symmetry inCeB6

et al. 2020

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In contrast to magnetic order formed by electrons' dipolar moments, ordering phenomena associated with higher-order multipoles (quadrupoles, octupoles, etc.) are more difficult to characterize because of the limited choice of experimental probes that can distinguish different multipolar moments. The heavy-fermion compound CeB 6 and its La-diluted alloys are among the best-studied realizations of the long-range-ordered multipolar phases, often referred to as "hidden order". Previously the hidden order in phase II was identified as primary antiferroquadrupolar (AFQ) and field-induced octupolar (AFO) order. Here we present a combined experimental and theoretical investigation of collective excitations in the phase II of CeB 6 . Inelastic neutron scattering (INS) in fields up to 16.5 T reveals a new high-energy mode above 14 T in addition to the lowenergy magnetic excitations. The experimental dependence of their energy on the magnitude and angle of the applied magnetic field is compared to the results of a multipolar interaction model. The magnetic excitation spectrum in rotating field is calculated within a localized approach using the pseudo-spin presentation for the Γ 8 states. We show that the rotating-field technique at fixed momentum can complement conventional INS measurements of the dispersion at constant field and holds great promise for identifying the symmetry of multipolar order parameters and the details of inter-multipolar interactions that stabilize hidden-order phases.

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Section: Introductionmentioning

confidence: 99%

Field-Angle-Resolved Magnetic Excitations as a Probe of Hidden-Order Symmetry inCeB6

et al. 2020

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“…In contrast, if the field is applied along one of the 001 directions, where both phase II and phase II are present, at least two dispersive excitations can be clearly observed (modes hω 1 and hω 2 in Ref. 40). Our present data for B [112] reveal four different field-induced modes in high magnetic fields.…”

Section: B Inelastic Scatteringmentioning

confidence: 50%

“…Indeed, as we know from earlier measurements, the spectrum in zero field is described by a single broad Lorentzian centered at an energy smaller than the peak width [47]. If the magnetic field is applied along one of the 110 directions for which the phase diagram shows only a single multipolar phase II, just a single inelastic line is induced by the field [40]. In contrast, if the field is applied along one of the 001 directions, where both phase II and phase II are present, at least two dispersive excitations can be clearly observed (modes hω 1 and hω 2 in Ref.…”

Section: B Inelastic Scatteringmentioning

confidence: 79%

“…An alternative strategy is to look at the magnetic excitations spectrum, with the objective of unraveling the propagation vector of the hidden-order phase indirectly from a minimum in the dispersion relations [5,40]. In the presence of a suitable theoretical model describing the magnetic excitations, the order parameter and multipolar interactions can in principle be extracted from a comparison of inelastic neutron scattering (INS) data with the model, yet the main challenge is the large number of free parameters describing the RKKY-type couplings between different multipoles across several nearest neighbors [41,42].…”

Section: Introductionmentioning

confidence: 99%

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Cascade of magnetic-field-driven quantum phase transitions in Ce3Pd20Si6

Mazza,

Portnichenko,

Avdoshenko

et al. 2022

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Magnetically hidden order is a hypernym for electronic ordering phenomena that are visible to macroscopic thermodynamic probes but whose microscopic symmetry cannot be revealed with conventional neutron or x-ray diffraction. In a handful of f -electron systems, the ordering of odd-rank multipoles leads to order parameters with a vanishing neutron cross-section. Among them, Ce 3 Pd 20 Si 6 is known for its unique phase diagram exhibiting two distinct multipolar-ordered ground states (phases II and II ), separated by a field-driven quantum phase transition associated with a putative change in the ordered quadrupolar moment from O 0 2 to O xy . Using torque magnetometry at subkelvin temperatures, here we find another phase transition at higher fields above 12 T, which appears only for low-symmetry magnetic field directions B 11L with 1 < L ≤ 2. While the order parameter of this new phase II remains unknown, the discovery renders Ce 3 Pd 20 Si 6 a unique material with two field-driven phase transitions between distinct multipolar phases. They are both clearly manifested in the magnetic-field dependence of the field-induced (111) Bragg intensities measured with neutron scattering for B [112]. We also find from inelastic neutron scattering that the number of nondegenerate collective excitations induced by the magnetic field correlates with the number of phases in the magnetic phase diagram for the same field direction. Furthermore, the magnetic excitation spectrum suggests that the new phase II may have a different propagation vector, revealed by the minimum in the dispersion that may represent the Goldstone mode of this hidden-order phase.

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“…One case in point is Ce 3 Pd 20 Si 6 where a field-driven switching between two magnetic phases, accompanied by a mode softening, has been observed in neutron scattering experiments. 24 In this context we note that symmetryenhanced first-order transitions in metals will induce deviations from Fermi-liquid behavior. The details of this will be investigated in future work.…”

Section: Discussionmentioning

confidence: 99%

Divergence of the Grüneisen ratio at symmetry-enhanced first-order quantum phase transitions

Beneke,

Vojta

2021

Preprint

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Studies of the Grüneisen ratio, i.e., the ratio between thermal expansion and specific heat, have become a powerful tool in the context of quantum criticality, since it was shown theoretically that the Grüneisen ratio displays characteristic power-law divergencies upon approaching the transition point of a continuous quantum phase transition. Here we show that the Grüneisen ratio also diverges at a symmetry-enhanced first-order quantum phase transition, albeit with mean-field exponents, as the enhanced symmetry implies the vanishing of a mode gap which is finite away from the transition. We provide explicit results for simple pseudo-spin models, both with and without Goldstone modes in the stable phases, and discuss implications.

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Evolution of the propagation vector of antiferroquadrupolar phases inCe3Pd20Si6under magnetic field

Cited by 6 publications

References 52 publications

Field-Angle-Resolved Magnetic Excitations as a Probe of Hidden-Order Symmetry inCeB6

Field-Angle-Resolved Magnetic Excitations as a Probe of Hidden-Order Symmetry inCeB6

Cascade of magnetic-field-driven quantum phase transitions in Ce3Pd20Si6

Divergence of the Grüneisen ratio at symmetry-enhanced first-order quantum phase transitions

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