NMR Evidence for Triple-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mover accent="true"><mml:mi>q</mml:mi><mml:mrow><mml:mo>→</mml:mo></mml:mrow></mml:mover></mml:math>Multipole Structure in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>NpO</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>

Tokunaga, Y.; Homma, Yoshiya; Kambe, S.; Aoki, Dai; Sakai, Hironori; Yamamoto, Etsuji; Nakamura, Akio; Shiokawa, Y.; Walstedt, R. E.; Yaśuoka, Hiroshi

doi:10.1103/physrevlett.94.137209

Cited by 96 publications

(78 citation statements)

References 17 publications

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“…(3.1), we obtain the bases of the lowest quartet as The four-fold degeneracy in the ground Γ (2) 8 quartet may be lifted by the intersite interaction, giving rise to induced multipole moments. Actually, several experiments tell us that the time-reversal symmetry is broken with nearly zero dipole moment in the ordered phase below T 0 = 25.5 K. 17,21 These observations lead Santini and Amoretti to propose the antiferro ordering of T xyz -type (T xyz ≡ √ 15…”

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confidence: 99%

Resonant x-ray scattering spectra from multipole ordering: NpM4,5edges inNpO2

Nagao

Igarashi

2005

Phys. Rev. B

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We study resonant x-ray scattering (RXS) at Np M4,5 edges in the triple-k multipole ordering phase in NpO2, on the basis of a localized electron model. We derive an expression for RXS amplitudes to characterize the spectra under the assumption that a rotational invariance is preserved in the intermediate state of scattering process. This assumption is justified by the fact that energies of the crystal electric field and the intersite interaction is smaller than the energy of multiplet structures. This expression is found useful to calculate energy profiles with taking account of the intra-Coulomb and spin-orbit interactions. Assuming the Γ8-quartet ground state, we construct the triple-k ground state, and analyze the RXS spectra. The energy profiles are calculated in good agreement with the experiment, providing a sound basis to previous phenomenological analyses.

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confidence: 99%

Resonant x-ray scattering spectra from multipole ordering: NpM4,5edges inNpO2

Nagao

Igarashi

2005

Phys. Rev. B

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“…In addition to dipole and quadrupole ordering, in recent years, possibility of higher-order multipole ordering, i.e., magnetic octupole ordering, has been also discussed for Ce x La 1−x B 6 7,8,9,10,11,12,13 and NpO 2 , 14,15,16,17,18,19,20 to reconcile experimental observations which seem to contradict one another at first glance. Very recently, a possibility of octupole ordering has been proposed also for SmRu 4 P 12 .…”

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confidence: 83%

Multipole ordering inf-electron systems on the basis of aj−jcoupling scheme

Kubo

Hotta

2005

Phys. Rev. B

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We investigate microscopic aspects of multipole ordering in f -electron systems with emphasis on the effect of lattice structure. For the purpose, first we construct f -electron models on three kinds of lattices, simple cubic (sc), bcc, and fcc, by including f -electron hopping through (f f σ) bonding in a tight-binding approximation on the basis of a j-j coupling scheme. Then, an effective model is derived in the strong-coupling limit for each lattice structure with the use of second-order perturbation theory with respect to (f f σ). By applying mean-field theory to such effective models, we find different types of multipole ordered state depending on the lattice structure. For the sc lattice, a Γ3g antiferro-quadrupole transition occurs at a finite temperature and as further lowering temperature, we find another transition to a ferromagnetic state. For the bcc lattice, a Γ2u antiferrooctupole ordering occurs first, and then, a ferromagnetic phase transition follows it. Finally, for the fcc lattice, we find a single phase transition to the longitudinal triple-q Γ5u octupole ordering.

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“…11) As for the materials properties, PuO 2 is known to be an insulator, same as other actinide dioxides, such as UO 2 . In addition, PuO 2 does not have any order even at low temperature, while UO 2 and NpO 2 have 3-q antiferromagnetic 12) and multipole orders, 13) respectively.…”

Section: Methodsmentioning

confidence: 99%

LDA+U Study on Plutonium Dioxide with Spin-Orbit Couplings

Nakamura

Machida

Kato

2011

Progress in Nuclear Science and Technology

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We perform first-principles density functional calculations on plutonium dioxides considering proper relativistic effects and strong correlations with the LDA+U method. Though this material is a paramagnetic insulator, standard local density approximation (LDA) predicts metallic states. In this paper, we point out that not only strong correlations but also spin-orbit couplings as relativistic effects are necessary to obtain paramagnetic insulating states. Based on this proper method, we also calculate physical properties of plutonium dioxide and compare them with experiments.

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NMR Evidence for Triple-q→Multipole Structure inNpO2

Cited by 96 publications

References 17 publications

Resonant x-ray scattering spectra from multipole ordering: NpM4,5edges inNpO2

Resonant x-ray scattering spectra from multipole ordering: NpM4,5edges inNpO2

Multipole ordering inf-electron systems on the basis of aj−jcoupling scheme

LDA+U Study on Plutonium Dioxide with Spin-Orbit Couplings

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