Resonant X-ray Studies of the Quadrupolar Orderings in RB<sub>2</sub>C<sub>2</sub>(R = Dy, Ho)

Matsumura, T.; Oumi, N.; Hirota, K.; Nakao, Hironori; Wakabayashi, Yusuke; Murakami, Youichi

doi:10.1143/jpsjs.71s.91

Cited by 13 publications

(7 citation statements)

References 8 publications

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“…the 2/m Ho site symmetry). Such a cos 2 2ϕ dependence has been observed for the quadrupole E2 resonance (2p to 4f transition) at the L edge [13]. The azimuthal dependence at E= 1357 eV (corresponding to D in Figure 3) departs from this simple relationship, further confirming the interference of magnetic and orbital order parameters.…”

Section: Resultssupporting

confidence: 61%

“…At room temperature, HoB 2 C 2 crystallizes in the tetragonal space group P4/mbm (see figure 1) and undergoes an antiferromagnetic (AFM) phase transition at T N = 5.6 K to the so-called phase IV, and a further transition to a combined AFM and antiferroquadrupolar (AFQ) ordered phase at T Q = 5 K (termed phase III) which has been confirmed directly with RXD at the Ho L edges [13] and also indirectly by ultrasonic measurement of the elastic constants [14]. Below T N the magnetic structure is incommensurate with ordering vector [1 + δ, δ, δ ] with δ = 0.11 and δ = 0.04.…”

Section: Introductionmentioning

confidence: 83%

“…The magnetic structures are compared in [28] and the component of k along (0 0 1 2 ) is found to be smaller in HoB 2 C 2 compared to DyB 2 C 2 . Moreover, resonant diffraction at the Ho L-edge has shown that the quadrupolar moment in HoB 2 C 2 is smaller than in DyB 2 C 2 [13].…”

Section: Discussionmentioning

confidence: 99%

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High-order Ho multipoles in HoB₂C₂observed with soft resonant x-ray diffraction

Princep¹,

Mulders²,

Schierle³

et al. 2012

J. Phys.: Condens. Matter

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Soft resonant x-ray Bragg diffraction (SRXD) at the Ho M4,5 edges has been used to study Ho 4f multipoles in the combined magnetic and orbitally ordered phase of HoB2C2. A full description of the energy dependence for both σ and π incident x-rays at two different azimuthal angles, as well as the ratio I(σ)/I(π) as a function of azimuthal angle for a selection of energies, allows a determination of the higher order multipole moments of rank 1 (dipole) to 6 (hexacontatetrapole). The Ho 4f multipole moments have been estimated, indicating a dominant hexadecapole (rank 4) order with an almost negligible influence from either the dipole or the octupole magnetic terms. The analysis incorporates both the intra-atomic magnetic and quadrupolar interactions between the 3d core and 4f valence shells as well as the interference of contributions to the scattering that behave differently under time reversal. Comparison of SRXD, neutron diffraction and non-resonant x-ray diffraction shows that the magnetic and quadrupolar order parameters are distinct. The (00½) component of the magnetic order exhibits a Brillouin type increase below the orbital ordering temperature T(Q), while the quadrupolar order increases more sharply. We conclude that the quadrupolar interaction is strong, but quadrupolar order only occurs when the magnetic order gives rise to a quasi-doublet ground state, which results in a lock-in of the orbitals at T(Q).

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Section: Resultssupporting

confidence: 61%

Section: Introductionmentioning

confidence: 83%

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High-order Ho multipoles in HoB₂C₂observed with soft resonant x-ray diffraction

Princep¹,

Mulders²,

Schierle³

et al. 2012

J. Phys.: Condens. Matter

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“…HoB 2 C 2 exhibits an AFQ ordering at T Q =4.5 K under zero magnetic field, even though a magnetic ordered state exists between T Q and T N =5.9 K(> T Q ), [4][5][6] which means that the AFQ ordering is realised under the internal magnetic field caused by the magnetic ordering. The AFQ ordering in HoB 2 C 2 was also confirmed by resonant X-ray scattering experiments by Matsumura et al 7 On the other hand, TbB 2 C 2 exhibits an AFM ordering at T N =21.7 K, but shows no evidence of an AFQ ordering under zero magnetic field so far. 8 TbB 2 C 2 is, however, the unique compound which shows a magnetic field induced AFQ ordering.…”

Section: Introductionsupporting

confidence: 53%

Detailed Measurements of Characteristic Profiles of Magnetic Diffuse Scattering in ErB₂C₂

et al. 2005

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Detailed neutron diffraction measurements on a single crystalline ErB2C2 were performed. We observed magnetic diffuse scattering which consists of three components just above the transition temperatures, which is also observed in characteristic antiferroquadrupolar ordering compounds HoB2C2 and TbB2C2. The result of this experiments indicates that the antiferroquadrupolar interaction is not dominantly important as a origin of the magnetic diffuse scattering.KEYWORDS: ErB2C2, TbB2C2, HoB2C2, antiferroquadrupolar ordering, diffuse scattering, long periodic magnetic structure, neutron diffraction IntroductionIn this paper, we report results of detailed neutron diffraction experiments for the rare earth compound ErB 2 C 2 , and discuss anomalous magnetic diffuse scattering which is also observed in the isostructural compounds, TbB 2 C 2 and HoB 2 C 2 , which exhibit characteristic antiferroquadrupolar (AFQ) orderings.The tetragonal compounds RB 2 C 2 (R=rare earth) with P 4/mbm symmetry 1-3 show various magnetic and quadrupolar behaviour due to coexistent competition between AFQ and antiferromagnetic (AFM) interactions. In particular, AFQ orderings in HoB 2 C 2 and TbB 2 C 2 are characteristic. HoB 2 C 2 exhibits an AFQ ordering at T Q =4.5 K under zero magnetic field, even though a magnetic ordered state exists between T Q and T N =5.9 K(> T Q ), 4-6 which means that the AFQ ordering is realised under the internal magnetic field caused by the magnetic ordering. The AFQ ordering in HoB 2 C 2 was also confirmed by resonant X-ray scattering experiments by Matsumura et al.7 On the other hand, TbB 2 C 2 exhibits an AFM ordering at T N =21.7 K, but shows no evidence of an AFQ ordering under zero magnetic field so far.

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“…It was also reported that an anisotropic charge distribution due to a small buckling lattice distortion of the B-and C-atoms contributes to the main peak of the resonant x-ray spectra of E1 transition in DyB 2 C 2 . 16,17,18,19,20 These results suggest that the O xy -and/or O 2 2 -type quadrupole ordering possessing a charge distribution in the basal plane is the order parameter of phase II of DyB 2 C 2 .…”

Section: Introductionmentioning

confidence: 96%