Field-Induced Magnetic Phase Transitions in a Triangular Lattice Antiferromagnet CuFeO<sub><b>2</b></sub>up to 14.5 T

Mitsuda, Setsuo; Mase, Motoshi; Prokeš, K.; Kitazawa, Hideaki; Katori, Hiroko Aruga

doi:10.1143/jpsj.69.3513

Cited by 103 publications

(100 citation statements)

References 9 publications

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“…The competition of the exchange interactions as well as the geometrical frustration among the Fe 3 þ spins (S ¼ 5/2) in the triangular-lattice plane (Fig. 1b), which stacks along [001] direction, results in the complex magnetic phase diagram including the screw spin structure 24,25 . The slight doping of the non-magnetic ions, such as the Al 26,27 and Ga 28,29 , stabilizes the screw spin phase, whose magnetic modulation vector has an incommensurate wave number (q, q, 3/2) with q ¼ 0.202 below 7.4 K (see Fig.…”

Section: Resultsmentioning

confidence: 99%

Magnetochiral dichroism resonant with electromagnons in a helimagnet

et al. 2014

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Cross-coupling between magnetism and electricity in a solid can be hosted by multiferroics with both magnetic and ferroelectric orders. In multiferroics, the collective spin excitations active for both electric and magnetic fields, termed electromagnons, play a crucial role in the elementary process of magnetoelectric (ME) coupling. Here we report the colossal dynamical (optical) ME effect, or more specifically the magnetochiral (MCh) effect, in the electromagnon resonance for the screw spin helimagnet CuFe 1 À x Ga x O 2 (x ¼ 0.035). The MCh effect shows up as the nonreciprocal directional dichroism; the extinction coefficient is different for counter-propagating lights, as large as by 400%. The MCh effect derived from the screw spin order is proved by control of the magnetic helicity of helimagnetism and its magnetization. The results point to the general presence of the MCh effect in helimagnets, paving a way to the ME control of electromagnetic wave in the giga-to tera-hertz region.

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Section: Resultsmentioning

confidence: 99%

Magnetochiral dichroism resonant with electromagnons in a helimagnet

et al. 2014

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“…Therefore, the spin current model is consistent with the fact that the ferroelectricity is observed only in the noncollinear phase. Nevertheless, previous neutron diffraction studies [11,15] suggest that the spin direction is always perpendicular to the wave vector in the noncollinear magnetic structures of both x=0.00 and x=0.02 crystals. This suggests that S i × S j e ij , and hence contradicts with the spin current model.…”

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confidence: 85%

“…When the field is increased up to 7 T, a noncollinear spin structure (NC) emerges [16]. Above 12 T, a 5-sublattice collinear structure (CM-5) is realized [11]. Recently, Kimura et al reported that the spontaneous polarization is observed in the noncollinear magnetic phase in between the 4-sublattice and 5-sublattice phases [18].…”

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confidence: 99%

Impurity-doping-induced ferroelectricity in the frustrated antiferromagnetCuFeO2

et al. 2007

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Dielectric responses have been investigated on the triangular-lattice antiferromagnet CuFeO2 and its site-diluted analogs CuFe1−xAlxO2 (x=0.01 and 0.02) with and without application of magnetic field. We have found a ferroelectric behavior at zero magnetic field for x=0.02. At any doping level, the onset field of the ferroelectricity always coincides with that of the noncollinear magnetic structure while the transition field dramatically decreases to zero field with Al doping. The results imply the further possibility of producing the ferroelectricity by modifying the frustrated spin structure in terms of site-doping and external magnetic field. In all these materials, the ferroelectric behavior is observed in the noncollinear magnetic phase. Katsura et al. proposed the spin current theory for the origin of ferroelectricity in the noncollinear magnetic phase [9]. In the theory, the electric dipole is induced by the spin current, which is expected to flow between noncollinear magnetic moments in analogy to the magnetic dipole induced by electric current. To produce such a ferroelectricity of magnetic origin, modification or partial lifting of spin state degeneracy may be prerequisite with use of the frustrated spin systems.Delafossite CuFeO 2 (See Fig. 1(d) for the structure) is one of candidates for such magnetic ferroelectrics. The crystal structure is characterized by the space group R3m, with two-dimensional triangular lattice layers stacked rhombohedrally along the caxis ( Fig. 1(d)). The magnetic structure of this material has been studied extensively by neutron diffraction measurements [10,11,12,13,14,15]. At zero field, a 4-sublattice collinear structure (CM-4) is observed at the lowest temperature. When the field is increased up to 7 T, a noncollinear spin structure (NC) emerges [16]. Above 12 T, a 5-sublattice collinear structure (CM-5) is realized [11]. Recently, Kimura et al. reported that the spontaneous polarization is observed in the noncollinear magnetic phase in between the 4-sublattice and 5-sublattice phases [18]. Similarly to the magnetic field, Al doping is known to easily modify the magnetic structure [13]. The 2 % substitution of Fe with Al induces the transition from CM-4 to NC at zero field and low temperature [12]. To clarify the relation between the magnetic structure and dielectric properties, the search for electric polarization is desirable also for the Al-doped crystals. In this work, we report the finding of ferroelectricity in the noncollinear magnetic phase of the Al doped crystal even in the absence of external magnetic field as well as the systematic evolution of the magneto-electric phase with Al-doping. This ensures the close relation between the noncollinear magnetic structure and ferroelectricity.Single crystals of CuFe 1−x Al x O 2 (x=0.00, 0.01, 0.02) were prepared by a floating zone method [19]. For the measurements of pyroelectric current and dielectric constant, the crystals were cut into thin planes with the widest faces parallel to (110) plane. As the electrodes, we ...

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“…Owing to the geometrical frustration in the triangular lattice planes of the magnetic Fe 3+ ions, CuFeO 2 exhibits various magnetically ordered phases. 13,14,15 The ground state of CuFeO 2 is a collinear-commensurate 4-sublattice (4SL) antiferromagnetic state. A spontaneous electric polarization emerging in the direction perpendicular to the hexagonal c axis was discovered in the first field-induced phase.…”

Section: Introductionmentioning

confidence: 99%

Identification of microscopic spin-polarization coupling in the ferroelectric phase of magnetoelectric multiferroicCuFe1−xAlxO2
Nakajima
¹
,
Mitsuda
²
,
Inami
³

et al. 2008
Phys. Rev. B
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We have performed synchrotron radiation X-ray and neutron diffraction measurements on magnetoelectric multiferroic CuFe1−xAlxO2 (x = 0.0155), which has a proper helical magnetic structure with incommensurate propagation wave vector in the ferroelectric phase. The present measurements revealed that the ferroelectric phase is accompanied by lattice modulation with a wave number 2q, where q is the magnetic modulation wave number. We have calculated the Fourier spectrum of the spatial modulations in the local electric polarization using a microscopic model proposed by Arima [T. Arima, J. Phys. Soc. Jpn. 76, 073702 (2007)]. Comparing the experimental results with the calculation results, we found that the origin of the 2q-lattice modulation is not conventional magnetostriction but the variation in the metal-ligand hybridization between the magnetic Fe (2008)], we conclude that the microscopic origin of the ferroelectricity in CuFe1−xAlxO2 is the variation in the metal-ligand hybridization with spin-orbit coupling.

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Field-Induced Magnetic Phase Transitions in a Triangular Lattice Antiferromagnet CuFeO₂up to 14.5 T

Cited by 103 publications

References 9 publications

Magnetochiral dichroism resonant with electromagnons in a helimagnet

Magnetochiral dichroism resonant with electromagnons in a helimagnet

Impurity-doping-induced ferroelectricity in the frustrated antiferromagnetCuFeO2

Identification of microscopic spin-polarization coupling in the ferroelectric phase of magnetoelectric multiferroicCuFe1−xAlxO2
Nakajima
¹
,
Mitsuda
²
,
Inami
³

et al. 2008
Phys. Rev. B
Self Cite
37
0
33
1
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Field-Induced Magnetic Phase Transitions in a Triangular Lattice Antiferromagnet CuFeO2up to 14.5 T

Cited by 103 publications

References 9 publications

Magnetochiral dichroism resonant with electromagnons in a helimagnet

Magnetochiral dichroism resonant with electromagnons in a helimagnet

Impurity-doping-induced ferroelectricity in the frustrated antiferromagnetCuFeO2

Identification of microscopic spin-polarization coupling in the ferroelectric phase of magnetoelectric multiferroicCuFe1−xAlxO2Nakajima1, Mitsuda2, Inami3 et al. 2008Phys. Rev. BSelf Cite370331View full textAdd to dashboardCite

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Field-Induced Magnetic Phase Transitions in a Triangular Lattice Antiferromagnet CuFeO₂up to 14.5 T

Identification of microscopic spin-polarization coupling in the ferroelectric phase of magnetoelectric multiferroicCuFe1−xAlxO2
Nakajima
¹
,
Mitsuda
²
,
Inami
³

et al. 2008
Phys. Rev. B
Self Cite
37
0
33
1
View full text Add to dashboard Cite