Nature of magnetoelectric coupling in corundum antiferromagnet Co4Ta2O9

Chaudhary, Sujeet; Srivastava, Pawan Kumar; Kaushik, S. D.; Siruguri, V.; Patnaik, S.

doi:10.1016/j.jmmm.2018.09.071

Cited by 14 publications

(20 citation statements)

References 39 publications

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“…2c. Note that this result is different from the previous results on polycrystalline samples, where the spin-flop transition occurs at a higher H of ~ 0.9 T, possibly due to the averaging effect over grain orientations 31 . On the other hand, the M c increases almost linearly up to 9 T resulting in a magnetic moment of ~ 2.1 μ B /f.u.…”

Section: Resultscontrasting

confidence: 99%

“…Further studies of the magnetoelectric effect in honeycomb lattices were done on the isostructural compound Co 4 Ta 2 O 9 (CTO) 6,30,31 . In CTO, the antiferromagnetic order emerges at T N ≈ 20 K, simultaneously with the appearance of a dielectric anomaly and a ferroelectric polarization in applied magnetic fields.…”

Section: Strongly Correlated Materials With Multiple Order Parametersmentioning

confidence: 99%

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Highly nonlinear magnetoelectric effect in buckled-honeycomb antiferromagnetic Co4Ta2O9

Lee

Choi

et al. 2020

Sci Rep

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Strongly correlated materials with multiple order parameters provide unique insights into the fundamental interactions in condensed matter systems and present opportunities for innovative technological applications. A class of antiferromagnetic honeycomb lattices compounds, A4B2O9 (A = Co, Fe, Mn; B = Nb, Ta), have been explored owing to the occurrence of linear magnetoelectricity. From our investigation of magnetoelectricity on single crystalline Co4Ta2O9, we discovered strongly nonlinear and antisymmetric magnetoelectric behavior above the spin-flop transition for magnetic fields applied along two orthogonal in-plane directions. This observation suggests that two types of inequivalent Co2+ sublattices generate magnetic-field-dependent ferroelectric polarization with opposite signs. The results motivate fundamental and applied research on the intriguing magnetoelectric characteristics of these buckled-honeycomb lattice materials.

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Section: Resultscontrasting

confidence: 99%

Section: Strongly Correlated Materials With Multiple Order Parametersmentioning

confidence: 99%

Highly nonlinear magnetoelectric effect in buckled-honeycomb antiferromagnetic Co4Ta2O9

Lee

Choi

et al. 2020

Sci Rep

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“…The space group is trigonal P 3 c 1 (No. 165) consistent with a recent report 12 . There are two crystallographically distinct sites occupied by the Co 2+ ions.…”

Section: Introductionsupporting

confidence: 90%

“…The origin of the distinct ME effects in these two compounds, therefore, deserves a detailed investigation. The magnetic structure of Co 4 Ta 2 O 9 has been recently determined by neutron powder diffraction 12 . It proposed a noncollinear magnetic structure in the ab-plane, similar to the one de-termined for Co 4 Nb 2 O 9 14,15 in the same magnetic space group, C2/c .…”

Section: Introductionmentioning

confidence: 99%

Noncollinear antiferromagnetic order in the buckled honeycomb lattice of magnetoelectric Co4Ta2O9 determined by single-crystal neutron diffraction

Choi,

Oh,

Gutmann

et al. 2020

Preprint

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Co4Ta2O9 exhibits a three-dimensional magnetic lattice based on the buckled honeycomb motif. It shows unusual magnetoelectric effects, including, in particular, the sign change and nonlinearity. These effects cannot be understood without the detailed knowledge of the magnetic structure. Herein, we report neutron diffraction and direction-dependent magnetic susceptibility measurements on Co4Ta2O9 single crystals. Below 20.3 K, we find a long-range antiferromagnetic order in the alternating buckled and flat honeycomb layers of Co 2+ ions stacked along the c-axis. Within experimental accuracy, the magnetic moments lie in the ab-plane. They form a noncollinear antiferromagnetic structure with a tilt angle of ∼ 14 • at 15 K in the buckled layers, while the magnetic moments in each flat layer are collinear. This is directly supported by a finite (0, 0, 3) magnetic Bragg peak intensity, which would be absent in the collinear magnetic order. The magnetic space group is C2 /c, which is different from the one previously found in powder neutron diffraction, as well as in the isostructural Co4Nb2O9. The revised magnetic structure successfully explains the major features of the magnetoelectric tensor within the framework of the spin-flop model.

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“…Later on, Deng et al showed that the magnetic moments of Co atoms are noncollinearly arranged in the ab plane [23]. A recent neutron-diffraction study on Co 4 Ta 2 O 9 also evidenced noncollinearly canted spin arrangement of Co atoms in the ab plane [24].…”

Section: Discussionmentioning

confidence: 99%

Low-temperature crystal and magnetic structures of the magnetoelectric material Fe4Nb2O9

Jana

Sheptyakov

et al. 2019

Phys. Rev. B

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Fe 4 Nb 2 O 9 was recently reported to be a new magnetoelectric material with two distinct dielectric anomalies located at T N ≈ 90 K for an antiferromagnetic transition and T str ≈ 77 K of unknown origin, respectively. By analyzing low-temperature neutron-powder-diffraction data, here we determined its magnetic structure below T N and uncovered the origin of the second dielectric anomaly as a structural phase transition across T str . In the antiferromagnetically ordered state below T N , both Fe1 and Fe2 magnetic moments lying within the weakly and strongly buckled honeycomb layers are arranged in a fashion that the three nearest neighbors are directed oppositely. Upon cooling below T str , the symmetry of crystal structure is lowered from trigonal P-3c1 to monoclinic C2/c, in which a weak sliding of the metal octahedral planes introduces a monoclinic distortion of ∼1.7 • . The magnetic structure is preserved in the low-temperature monoclinic phase, and the Fe magnetic moment increases from 2.1(1)μ B at 95 K to 3.83(4)μ B at 10 K assuming an equal moment configuration at Fe1 and Fe2 sites. The magnetic point group and linear magnetoelectric tensor at each temperature region are determined. From a symmetry-related tensor analysis, the microscopic origins of the magnetoelectric effects between T N and T str are proved to be spin-current and d-p hybridization mechanisms.

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Nature of magnetoelectric coupling in corundum antiferromagnet Co4Ta2O9

Cited by 14 publications

References 39 publications

Highly nonlinear magnetoelectric effect in buckled-honeycomb antiferromagnetic Co4Ta2O9

Highly nonlinear magnetoelectric effect in buckled-honeycomb antiferromagnetic Co4Ta2O9

Noncollinear antiferromagnetic order in the buckled honeycomb lattice of magnetoelectric Co4Ta2O9 determined by single-crystal neutron diffraction

Low-temperature crystal and magnetic structures of the magnetoelectric material Fe4Nb2O9

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