Neutron diffraction studies on GdB6 and TbB6 powders

Luca, Sorana; Amara, M.; Galéra, Rose-Marie; Givord, F.; Granovsky, S.A.; Isnard, O.; Beneu, B.

doi:10.1016/j.physb.2004.03.009

Cited by 27 publications

(26 citation statements)

References 5 publications

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“…Indeed, to be consistent with GdB 6 powder neutron diffraction results, 13 the magnetic moments are in the basal plane ͑001͒.…”

Section: Factorization Of the Mean-fieldsupporting

confidence: 79%

“…Indeed, as one would extrapolate from the GdB 6 case, these other ͗ 1 4 1 4 1 2 ͘ antiferromagnets also order in a first-order process. 13,19,20 However, it has to be reminded that for such L 0 ions, orbital effects, which we did not consider here, should also take part in defining the ordered states and the order of the transition at T N . To this respect, the case of DyB 6 might be the most eloquent, the first-order transformation being reported as nonmagnetic, but ferroquadrupolar.…”

Section: Criticality At T Nmentioning

confidence: 99%

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Exchange-displacement waves inGdB6

et al. 2005

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The antiferromagnetic states of GdB 6 are investigated both theoretically and experimentally. A mean-field model is introduced which predicts the coexistence of magnetic and displacement waves starting from isotropic exchange and magnetic ions in a harmonic potential. It provides a coherent interpretation of the puzzling features of GdB 6 magnetic order, in particular the first-order magnetic transition at T N and the two successive antiferromagnetic states. X-ray scattering experiments show ͗ 1 2 0 0 ͘ , ͗ 1 2 1 2 0 ͘ , and ͗ 1 4 1 4 1 2 ͘ satellites consistent with displacement waves imposed by the magnetic ͗ 1 4 1 4 1 2 ͘ structures. In the high-temperature phase, the observation of second-order displacement reflections is evidence of a multi-q, ͗ 1 2 0 0 ͘ , displacement structure: a model of magnetic structure, consistent with both the displacement pattern and the mean-field model predictions, is proposed.

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“…Indeed, to be consistent with GdB 6 powder neutron diffraction results, 13 the magnetic moments are in the basal plane ͑001͒.…”

Section: Factorization Of the Mean-fieldsupporting

confidence: 79%

Section: Criticality At T Nmentioning

confidence: 99%

Exchange-displacement waves inGdB6

et al. 2005

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“…In particular, Kasuya [17] applied the Jahn-Teller formalism to RB 6 compounds and proposed a stable coexistence of charge dipole and magnetic dipole ordering in both AF states of GdB 6 . However, the magnetic dipole ordering of Gd-Gd pairs does not correspond to the vector of magnetic structure k m obtained later from neutron studies [13,14]. Modern theory was proposed by Amara et al in [11] for AF I state of GdB 6 .…”

Section: Introductionmentioning

confidence: 90%

“…Gadolinium hexaboride (GdB 6 ) is the S-state system (for Gd 3+ , L = 0, S = 7/2) which represents very unusual physical properties [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Similar to another rare earth (RE) hexaborides GdB 6 crystallizes in a simple bcc structure of CsCl type (s.g. P m3m−O 1 h ) and shows the flat phonon dispersion relations around 10 meV [15] corresponding to the motion of RE ions inside a rigid boron cage.…”

Section: Introductionmentioning

confidence: 99%

“…(The value of T N 2 is found to be strongly sample dependent ranging in the interval T N 2 ≈ 5−10 K [1][2][3][4][5][6][7][8][9][10][11][12][13][14]). Recent structural investigations (including X-ray [8][9][10][11][12] and neutron diffraction [13,14] experiments) have shown that commensurate magnetic structure with the wave vector k m = [1/4, 1/4, 1/2] is realized both in AF I and AF II states of GdB 6 . The changes between AF I and AF II phases are connected with appearance of different reflexes corresponding to the structural modulation.…”

Section: Introductionmentioning

confidence: 99%

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Anisotropy of the Charge Transport in GdB₆

et al. 2017

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The anisotropy of charge transport was investigated in the antiferromagnetic II state of GdB6 from precise measurements of transverse magnetoresistance. Based on the data obtained we detected a complicated behavior of magnetoresistance curves which are characterized by the appearance of considerable hysteresis on the field and angular dependences below TN2. Moreover it was shown that the system GdB6 is sensitive to coolingwarming prehistory. The data analysis allowed to reconstruct magnetic H−T phase diagram of GdB6 along main crystallographic directions (H 001 , 110 , 111 ) and to propose additional phase transition inside AF II phase at H1 ≈ 0.5 T.

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Charge distribution consequences of the magnetic order in TbB₆

Galéra

Amara

Aviani

et al. 2006

Phys. Status Solidi (c)

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The antiferromagnetic state of TbB6 has been investigated by way of magnetostriction and X-ray scattering measurements on a single crystal. The magnetostriction data reveal a well defined tetragonal symmetry lowering and a weak volume increase below TN . The X-ray scattering investigation shows charge satellites, related to the IntroductionIn rare-earth compounds, the crystal field reduces the orbital degeneracy of the magnetic ions. The 4f electronic distribution thus adapts to the rare-earth site symmetry [1, 2], yielding anisotropic magnetic properties. In high symmetry systems, the orbital degeneracy is only partly lifted and due to the spin-orbit coupling, the remaining orbital degrees of freedom are involved in the low temperature phenomena even in the ordered phase. In most rare-earth intermetallics concomitantly with the magnetic ordering, quadrupolar moments develop. Due to the magnetoelastic couplings, the quadrupolar components at the center of the Brillouin zone (ferroquadrupolar) lead to sizable magnetostriction phenomena. The quadrupolar components outside the zone center (antiferroquadrupolar) determine multiaxial magnetic structures. They also introduce a new charge periodicity that is observed by X-ray diffraction. It is worth noting that quadrupolar components may also influence the order of the magnetic transition [3][4][5][6].It turns out that, in special crystallographic and magnetic structures a slight displacement of the 4f ion can be very effective in minimizing the exchange energy with a low elastic energy cost [7]. The compromise stabilize static atomic displacement waves (DW) in antiferromagnetic systems, as recently shown in the ordered phase of GdB 6 [8]. In this compound displacements organize in rather complex multiaxial patterns, as revealed by X-ray diffraction on a single crystal. While L = 0 for Gd 3+ , displacement waves are responsible for the first-order type transition at T N .The model of exchange displacements, developed for GdB 6 , applies to other REB 6 compounds since their magnetic wave-vectors k belong to the particular

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Neutron diffraction studies on GdB6 and TbB6 powders

Cited by 27 publications

References 5 publications

Exchange-displacement waves inGdB6

Exchange-displacement waves inGdB6

Anisotropy of the Charge Transport in GdB₆

Charge distribution consequences of the magnetic order in TbB₆

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Neutron diffraction studies on GdB6 and TbB6 powders

Cited by 27 publications

References 5 publications

Exchange-displacement waves inGdB6

Exchange-displacement waves inGdB6

Anisotropy of the Charge Transport in GdB6

Charge distribution consequences of the magnetic order in TbB6

Contact Info

Product

Resources

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Anisotropy of the Charge Transport in GdB₆

Charge distribution consequences of the magnetic order in TbB₆