Collective excitations in the tetravalent lanthanide honeycomb antiferromagnet Na2Pr O3

M. J. Daum; A. Ramanathan; A. I. Kolesnikov; S. Calder; M. Mourigal; H. S. La Pierre

doi:10.1103/PhysRevB.103.L121109

Collective excitations in the tetravalent lanthanide honeycomb antiferromagnet Na2Pr O3

M. J. Daum
, A. Ramanathan
, A. I. Kolesnikov
, S. Calder
, M. Mourigal
, H. S. La Pierre

Research output: Contribution to journal › Article › peer-review

30 Scopus citations

Abstract

Thermomagnetic and inelastic neutron-scattering measurements on Na2PrO3 are reported. This material is an antiferromagnetic honeycomb magnet based on the tetravalent lanthanide Pr4+ and has been proposed to host dominant antiferromagnetic Kitaev interactions. These measurements reveal magnetic fluctuations in Na2PrO3 below an energy of 2 meV as well as crystal-field excitations around 230 meV. The latter energy is comparable to the scale of the spin-orbit interaction and explains both the very small effective moment of around 1.0μB per Pr4+ and the difficulty to uncover any static magnetic scattering below the ordering transition at TN= 4.6 K. By comparing the low-energy magnetic excitations in Na2PrO3 to those of the isostructural spin-only compound, Na2TbO3, a microscopic model of exchange interactions is developed that implicates dominant and surprisingly large Heisenberg exchange interactions J≈1.1(1) meV. Although antiferromagnetic Kitaev interactions with K≤0.2J cannot be excluded, the inelastic neutron-scattering data of Na2PrO3 is best explained with a Δ=1.22 easy-axis XXZ exchange anisotropy.

Original language	English
Article number	L121109
Journal	Physical Review B
Volume	103
Issue number	12
DOIs	https://doi.org/10.1103/PhysRevB.103.L121109
State	Published - Mar 12 2021

Funding

We thank Zhiling Dun for numerous helpful discussions and are indebted to Andrew Boothroyd for refining the definition of the Wybourne operators in an initial version of this paper. The work of A.R. and H.S.L. at Georgia Tech was supported by the Beckman Foundation as part of a Beckman Young Investigator Award to H.S.L. The work of M.D. and M.M. at Georgia Tech was supported by the National Science Foundation through Grant No. NSF-DMR-1750186. This research used resources at the High Flux Isotope Reactor and the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.

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10.1103/PhysRevB.103.L121109

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title = "Collective excitations in the tetravalent lanthanide honeycomb antiferromagnet Na2Pr O3",

abstract = "Thermomagnetic and inelastic neutron-scattering measurements on Na2PrO3 are reported. This material is an antiferromagnetic honeycomb magnet based on the tetravalent lanthanide Pr4+ and has been proposed to host dominant antiferromagnetic Kitaev interactions. These measurements reveal magnetic fluctuations in Na2PrO3 below an energy of 2 meV as well as crystal-field excitations around 230 meV. The latter energy is comparable to the scale of the spin-orbit interaction and explains both the very small effective moment of around 1.0μB per Pr4+ and the difficulty to uncover any static magnetic scattering below the ordering transition at TN= 4.6 K. By comparing the low-energy magnetic excitations in Na2PrO3 to those of the isostructural spin-only compound, Na2TbO3, a microscopic model of exchange interactions is developed that implicates dominant and surprisingly large Heisenberg exchange interactions J≈1.1(1) meV. Although antiferromagnetic Kitaev interactions with K≤0.2J cannot be excluded, the inelastic neutron-scattering data of Na2PrO3 is best explained with a Δ=1.22 easy-axis XXZ exchange anisotropy.",

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AU - Daum, M. J.

AU - Ramanathan, A.

AU - Kolesnikov, A. I.

AU - Calder, S.

AU - Mourigal, M.

AU - La Pierre, H. S.

PY - 2021/3/12

Y1 - 2021/3/12

N2 - Thermomagnetic and inelastic neutron-scattering measurements on Na2PrO3 are reported. This material is an antiferromagnetic honeycomb magnet based on the tetravalent lanthanide Pr4+ and has been proposed to host dominant antiferromagnetic Kitaev interactions. These measurements reveal magnetic fluctuations in Na2PrO3 below an energy of 2 meV as well as crystal-field excitations around 230 meV. The latter energy is comparable to the scale of the spin-orbit interaction and explains both the very small effective moment of around 1.0μB per Pr4+ and the difficulty to uncover any static magnetic scattering below the ordering transition at TN= 4.6 K. By comparing the low-energy magnetic excitations in Na2PrO3 to those of the isostructural spin-only compound, Na2TbO3, a microscopic model of exchange interactions is developed that implicates dominant and surprisingly large Heisenberg exchange interactions J≈1.1(1) meV. Although antiferromagnetic Kitaev interactions with K≤0.2J cannot be excluded, the inelastic neutron-scattering data of Na2PrO3 is best explained with a Δ=1.22 easy-axis XXZ exchange anisotropy.

AB - Thermomagnetic and inelastic neutron-scattering measurements on Na2PrO3 are reported. This material is an antiferromagnetic honeycomb magnet based on the tetravalent lanthanide Pr4+ and has been proposed to host dominant antiferromagnetic Kitaev interactions. These measurements reveal magnetic fluctuations in Na2PrO3 below an energy of 2 meV as well as crystal-field excitations around 230 meV. The latter energy is comparable to the scale of the spin-orbit interaction and explains both the very small effective moment of around 1.0μB per Pr4+ and the difficulty to uncover any static magnetic scattering below the ordering transition at TN= 4.6 K. By comparing the low-energy magnetic excitations in Na2PrO3 to those of the isostructural spin-only compound, Na2TbO3, a microscopic model of exchange interactions is developed that implicates dominant and surprisingly large Heisenberg exchange interactions J≈1.1(1) meV. Although antiferromagnetic Kitaev interactions with K≤0.2J cannot be excluded, the inelastic neutron-scattering data of Na2PrO3 is best explained with a Δ=1.22 easy-axis XXZ exchange anisotropy.

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Collective excitations in the tetravalent lanthanide honeycomb antiferromagnet Na2Pr O3

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