Gigantic magnetoelectric effect caused by magnetic-field-induced canted antiferromagnetic-paramagnetic transition in quasi-two-dimensional Ca2CoSi2O7 crystal

Akaki, Mitsuru; Tozawa, J.; Akahoshi, Daisuke; Kuwahara, H.

doi:10.1063/1.3147195

Cited by 38 publications

(32 citation statements)

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“…For this reason, neither the S i × S j spincurrent mechanism nor the S i · S j exchange striction one can work for this compound. However, the ferroelectric polarization is observed below T N under magnetic field as reported for this [19] and related compounds [20] (see also Figs. 1(c) and (d) observed in the present study), while the microscopic origin has not been clarified.…”

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confidence: 79%

Ferroelectricity Induced by Spin-Dependent Metal-Ligand Hybridization inBa2CoGe2O7

et al. 2010

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We have investigated the variation of induced ferroelectric polarization under magnetic field with various directions and magnitudes in a staggered antiferromagnet Ba2CoGe2O7. While the ferroelectric polarization cannot be explained by the well-accepted spin current model nor exchange striction mechanism, we have shown that it is induced by the spin-dependent p-d hybridization between the transition-metal (Co) and ligand (O) via the spin-orbit interaction. On the basis of the correspondence between the direction of electric polarization and the magnetic state, we have also demonstrated the electrical control of the magnetization direction.Electrical control of magnetism has long been an important subject in condensed-matter physics as well as an urgent issue in contemporary spin-electronics. One of the promising ways toward this goal is to make use of magnetoelectric effect (change of magnetization by electric field, or reciprocally, change of electric polarization by magnetic field) in magnetic dielectrics [1][2][3][4][5]. The electric-field control of magnetism in terms of the magnetoelectric effect is much less dissipative in energy than the current control of magnetism in itinerant ferromagnets. While the magnetoelectric effect was thought to be quite small, the magnetically-induced ferroelectrics (multiferroics) and their giant magnetoelectric effect have recently been discovered and are now attracting much attention.There are several microscopic mechanisms for the magnetically-induced ferroelectricity. The most prevailing mechanism is the spin current mechanism[6], or equivalently the inverse Dzyaloshinskii-Moriya mechanism [7,8]. In the transverse-helical (cycloidal) spin structure, the spin chirality can induce the polarization P ∝ i,j e ij × (S i × S i ) in terms of the spin current mechanism, where e ij denotes the unit vector connecting the interacting neighbor spins S i and S j . In the crystal which contains multiple inequivalent magnetic sites, even the collinear spin structure may also induce ferroelectricity with use of magnetostriction caused by the symmetric exchange interaction [15]. In these materials, the ferroelectricity can be caused by the transition metal-ligand (p-d) hybridization depending on the spin direction [16,17]. Owing to the hybridization relevant to the spin-orbit interaction, the ionic charge ρ of the ligand can vary depending on the angle η between the spin of the transition metal and the vector e connecting the transition metal and the ligand, i.e. ∆ρ ∝ (S · e) 2 . Therefore, the local electric polarization ∆P ∝ (S · e) 2 e exists between the transition metal and the ligand. The induced charge of the local dipoles, when summed up over the whole crystal, may induce the ferroelectricity. To examine the mechanism in more detail, a more simple spin structure is desirable because this is a single ion problem rather than a spin correlation (S i × S j , S i · S j , etc.) one. In this paper, we show the ferroelectricity and its magnetic-field dependence in a simple staggered antif...

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confidence: 79%

Ferroelectricity Induced by Spin-Dependent Metal-Ligand Hybridization inBa2CoGe2O7

et al. 2010

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“…Since inåkermanite materials electric polarization emerges even without applying poling electric fields, which is a unique feature of their multiferroicity [8,[11][12][13], we measured the polarization current without poling electric fields.…”

Section: Sample Characterization Experimental Detailsmentioning

confidence: 99%

“…The * akaki@ahmf.sci.osaka-u.ac.jp lack of inversion symmetry at the tetrahedrally coordinated Co sites permits the magneto-electric effect, with on-site polarization proportional to the quadrupole operators already at a level of a single ion. The metal-ligand hybridization is believed to act in Ba 2 CoGe 2 O 7 [10,11], Sr 2 CoSi 2 O 7 [8], and Ca 2 CoSi 2 O 7 [12,13]. This mechanism is considered to be responsible for the dynamical properties of these materials, as it couples the spin degrees of freedom to the oscillating electric field component of the light.…”

Section: Introductionmentioning

confidence: 99%

Direct observation of spin-quadrupolar excitations in Sr2CoGe2O7 by high-field electron spin resonance

et al. 2017

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Exotic spin-multipolar ordering in spin transition metal insulators has so far eluded unambiguous experimental observation. A less studied, but perhaps more feasible fingerprint of multipole character emerges in the excitation spectrum in the form of quadrupolar transitions. Such multipolar excitations are desirable as they can be manipulated with the use of light or electric field and can be captured by means of conventional experimental techniques. Here we study single crystals of multiferroic Sr2CoGe2O7, and observe a two-magnon spin excitation appearing above the saturation magnetic field in electron spin resonance (ESR) spectra. Our analysis of the selection rules reveals that this spin excitation mode does not couple to the magnetic component of the light, but it is excited by the electric field only, in full agreement with the theoretical calculations. Due to the nearly isotropic nature of Sr2CoGe2O7, we identify this excitation as a purely spin-quadrupolar two-magnon mode.

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“…17) As seen from the schematic åkermanite structure illustrated in the inset of Fig. 1 were grown using the floating zone method.…”

Section: Draftmentioning

confidence: 99%

“…In åkermanite materials, electric polarization emerges even without poling electric fields, which is a unique feature of their multiferroicity. 12,13,17) Therefore, the polarization current was measured without applying a poling electric field. T N =7 K).…”

Section: Draftmentioning

confidence: 99%

Successive Magnetic Transitions of Ca₂CoSi₂O₇in High Magnetic Fields

et al. 2014

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Magnetic and dielectric properties of åkermanite Ca 2 CoSi 2 O 7 single crystals were investigated in pulsed high magnetic fields. In magnetic fields along the c axis, this material shows a magnetization plateau in a wide range of field below the saturation. Magnetization processes for fields along the a and b axes show multiple anomalies but different traces to each other, indicating the breaking of four-fold symmetry. Measurements of the magnetoelectric effects exhibit the changes in electric polarization according to the changes in the spin system. The experimentally determined quadratic magnetoelectric tensor is consistent with that expected in the crystal symmetry of orthorhombic P2 1 2 1

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Gigantic magnetoelectric effect caused by magnetic-field-induced canted antiferromagnetic-paramagnetic transition in quasi-two-dimensional Ca2CoSi2O7 crystal

Abstract: Magnetic field induced polarization and magnetoelectric effect of Ba0.8Ca0.2TiO3-Ni0.2Cu0.3Zn0.5Fe2O4 nanomultiferroic J. Appl. Phys. 113, 17C731 (2013); 10.1063/1.4795820 O 17 and N 93 b NMR investigation of magnetoelectric effect in Pb ( Fe 1 / 2 Nb 1 / 2 ) O 3

Cited by 38 publications

References 13 publications

Ferroelectricity Induced by Spin-Dependent Metal-Ligand Hybridization inBa2CoGe2O7

Ferroelectricity Induced by Spin-Dependent Metal-Ligand Hybridization inBa2CoGe2O7

Direct observation of spin-quadrupolar excitations in Sr2CoGe2O7 by high-field electron spin resonance

Successive Magnetic Transitions of Ca₂CoSi₂O₇in High Magnetic Fields

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Gigantic magnetoelectric effect caused by magnetic-field-induced canted antiferromagnetic-paramagnetic transition in quasi-two-dimensional Ca2CoSi2O7 crystal

Abstract: Magnetic field induced polarization and magnetoelectric effect of Ba0.8Ca0.2TiO3-Ni0.2Cu0.3Zn0.5Fe2O4 nanomultiferroic J. Appl. Phys. 113, 17C731 (2013); 10.1063/1.4795820 O 17 and N 93 b NMR investigation of magnetoelectric effect in Pb ( Fe 1 / 2 Nb 1 / 2 ) O 3

Cited by 38 publications

References 13 publications

Ferroelectricity Induced by Spin-Dependent Metal-Ligand Hybridization inBa2CoGe2O7

Ferroelectricity Induced by Spin-Dependent Metal-Ligand Hybridization inBa2CoGe2O7

Direct observation of spin-quadrupolar excitations in Sr2CoGe2O7 by high-field electron spin resonance

Successive Magnetic Transitions of Ca2CoSi2O7in High Magnetic Fields

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Successive Magnetic Transitions of Ca₂CoSi₂O₇in High Magnetic Fields