Ultrasonic Investigations of Ferroquadrupolar Ordering at 8c Site in Ce3Pd20Ge6

Nemoto, Y.; Yamaguchi, Takashi; Gotô, Terutaka; Сузукі, Осаму; Horino, Takenobu; Dönni, A.; Komatsubara, T.

doi:10.1143/jpsjs.71s.121

Cited by 3 publications

(4 citation statements)

References 6 publications

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“…In increasing magnetic field, the AFM transition temperature T N shifts to lower temperatures, while the FQ transition temperature T Q shifts to higher temperatures. The increase of T Q in magnetic fields is a common feature in materials showing FQ ordering [5]. obtained by θ = 0.132 • at 2.1 K in the neutron scattering experiments [14].…”

Section: Hobmentioning

confidence: 88%

“…Because the direct product of 8 is reduced as 8 ⊗ 8 = 1 ⊕ 2 ⊕ 3 ⊕ 2 4 ⊕ 2 5 , three dipoles J x , J y , J z , five quadrupoles O 0 2 , O β z are expected for the order parameter of the 8 quartet system [3]. The intermetallic compounds CeAg [4] and Ce 3 Pd 20 Ge 6 [5] with the 8 quartet are known as the FQ ordering associated with O 0 2 accompanied by a structural change from the cubic class to the tetragonal class. A rare earth hexaboride DyB 6 with a 8 ground state also shows FQ ordering of O yz , O zx , O xy with a trigonal distortion [6].…”

Section: Introductionmentioning

confidence: 99%

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Quadrupole and lattice effects of orbitally degenerate 4f-electron systems

Gotô¹,

Akatsu²,

Yanagisawa³

et al. 2003

J. Phys.: Condens. Matter

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The quadrupole orderings and lattice effects in 4f-electron systems with orbital degeneracy in rare earth compounds have been investigated by ultrasonic and thermal expansion measurements. A ferroquadrupole (FQ) O xy -type ordering associated with a trigonal distortion in HoB 6 with a 5 ground state is presented. The trigonal distortion in ordered phase IV Ce x La 1−x B 6 (x = 0.75 and 0.70) with a 8 ground state indicates O xy -type FQ ordering in phase IV. In both systems, HoB 6 and Ce x La 1−x B 6 , C 44 anomalies are observed. In tetragonal HoB 2 C 2 , an ordered phase IV appears near a tetra-critical point, where the antiferroquadrupole phase II and antiferromagnetic phase III compete with each other. Noticeable ultrasonic attenuation and softening of elastic constants in phase IV of HoB 2 C 2 due to quadrupole fluctuation with a slow relaxation time τ ∼ 7 × 10 −9 s are found.

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Section: Hobmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Quadrupole and lattice effects of orbitally degenerate 4f-electron systems

Gotô¹,

Akatsu²,

Yanagisawa³

et al. 2003

J. Phys.: Condens. Matter

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“…The terms related to the time-reversal operation in Eqs. ( 29), (30), and (31) are called the anti-unitary part of the MSG. The type II MSG is called grey space groups, and the nonmagnetic orders, including pure electric multipole orders, belongs to the grey groups since these orders preserve the pure time-reversal symmetry.…”

Section: Discussionmentioning

confidence: 99%

“…It turns out, however, that the appearance of true multipolar order, that is, of rank higher than dipolar order, is actually rare in solid state compounds. Thus far, true multipolar order has been discovered, or predicted, for about a dozen crystalline materials, such as, CeB 6 , [10][11][12][13][14][15][16][17][18][19][20][21] R 3 Pd 20 X 6 (R: Ce, Pr, X: Si, Ge), [22][23][24][25][26][27][28][29][30][31][32] PrPb 3 , [33][34][35][36][37][38][39][40][41][42] PrMg 3 , [43][44][45][46] PrFe 4 P 12 , [47][48][49][50][51][52][53][54][55][56][57][58]…”

Section: Introductionmentioning

confidence: 99%

First-principles Theory of Magnetic Multipoles in Condensed Matter Systems

2018

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The multipole concept, which characterizes the spacial distribution of scalar and vector objects by their angular dependence, has already become widely used in various areas of physics. In recent years it has become employed to systematically classify the anisotropic distribution of electrons and magnetization around atoms in solid state materials. This has been fuelled by the discovery of several physical phenomena that exhibit unusual higher rank multipole moments, beyond that of the conventional degrees of freedom as charge and magnetic dipole moment. Moreover, the higher rank electric/magnetic multipole moments have been suggested as promising order parameters in exotic hidden order phases. While the experimental investigations of such anomalous phases have provided encouraging observations of multipolar order, theoretical approaches have developed at a slower pace. In particular, a materials' specific theory has been missing. The multipole concept has furthermore been recognized as the key quantity which characterizes the resultant configuration of magnetic moments in a cluster of atomic moments. This cluster multipole moment has then been introduced as macroscopic order parameter for a noncollinear antiferromagnetic structure in crystals that can explain unusual physical phenomena whose appearance is determined by the magnetic point group symmetry. It is the purpose of this review to discuss the recent developments in the first-principles theory investigating multipolar degrees of freedom in condensed matter systems. These recent developments exemplify that ab initio electronic structure calculations can unveil detailed insight in the mechanism of physical phenomena caused by the unconventional, multipole degree of freedom.These compounds have in common that the exotic multipolar electric or magnetic distribution occurs on the lanthanide or actinide ion and are thus generated by the f electrons.More general, typical features of f electron systems are localized character, that tends to enforce the strong electron-electron repulsion, a significant orbital degree of freedom, allowing for anisotropic orbital states, and strong spin-orbit (S-O) coupling which leads to entangled spin and orbital moments. * michito.suzuki@riken.jp 2/67

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