Magnetic-field-induced toroidal moment in the magnetoelectric Cr2O3

Popov, Yu. F.; Kadomtseva, A. M.; Белов, Д. В.; Vorob’ev, G. P.; Zvezdin, A. K.

doi:10.1134/1.568032

Cited by 126 publications

(142 citation statements)

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“…This state is known to exhibit marginal quadratic magnetoelectric (ME) effect at low magnetic fields [12]. High magnetic fields of ∼20 T stabilize the canted antiferromagnetic (CAFM) phase as opposed to the cycloidal phase [13][14][15][16][17]. Although several groups succeeded in realizing the CAFM phase at zero field [18][19][20][21][22][23], the ME effect in this phase has not been clarified.…”

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Successive field-induced transitions in BiFeO3 around room temperature

Kawachi

Miyake

et al. 2017

Phys. Rev. Materials

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The effects of high magnetic fields applied perpendicular to the spontaneous ferroelectric polarization on single crystals of BiFeO3 were investigated through magnetization, magnetostriction, and neutron diffraction measurements. The magnetostriction measurements revealed lattice distortion of 2 × 10 −5 , during the reorientation process of the cycloidal spin order by applied magnetic fields. Furthermore, anomalous changes in magnetostriction and electric polarization at a larger field demonstrate an intermediate phase between cycloidal and canted antiferromagnetic states, where a large magnetoelectric effect was observed. Neutron diffraction measurements clarified that incommensurate spin modulation along [110] Recently, multiferroic materials have been widely investigated due to their coupling between magnetic and ferroelectric ordering. BiFeO 3 is perhaps the most extensively studied multiferroic material as it possesses robust multiferroicity at room temperature as well as various possible applications [1][2][3][4][5][6][7][8][9][10]. The effects of magnetic fields on the coupled multiple degrees of freedom behind these phenomena are not fully understood.BiFeO 3 exhibits a cycloidal magnetic order below 640 K [11]. This state is known to exhibit marginal quadratic magnetoelectric (ME) effect at low magnetic fields [12]. High magnetic fields of ∼20 T stabilize the canted antiferromagnetic (CAFM) phase as opposed to the cycloidal phase [13][14][15][16][17]. Although several groups succeeded in realizing the CAFM phase at zero field [18][19][20][21][22][23], the ME effect in this phase has not been clarified. In this study, several features were observed when a magnetic field was applied normal to the trigonal c-axis, and they indicated that a third magnetic phase emerged in bulk BiFeO 3 between the cycloidal and CAFM phases at approximately room temperature.BiFeO 3 has a crystal structure with the polar space group of R3c. A large switchable spontaneous electric polarization emerges along the c-axis of the trigonal cell [24][25][26]. Degeneracy exists in selecting the polarization direction from eight 111 directions in the cubic unit. Hence, depending on synthesis methods, BiFeO 3 crystals can contain multiple ferroelectric domains [27].Magnetic domains can be present even in single ferroelectric domain crystals. The magnetic propagation vector Q points in one of the 110 directions of the trigonal cell [11] in the cycloidal spin ordered state below ∼640 K. The three-fold rotational symmetry around the c-axis (Z direction in this paper) leads to three equivalent Q i (i = 1, 2, 3), as shown in Fig. 1(d). The spins rotated primarily in the Q i -Z plane in a magnetic domain with a given Q i .Recently, Tokunaga et al. indicated the emergence of an electric polarization perpendicular to the Z direction that was controlled by magnetic fields [17]. Theoretical calculations suggested that the cycloidal spin order in BiFeO 3 could involve electric polarization perpendicular to the Q i -Z plane as illustrated as P T in...

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Successive field-induced transitions in BiFeO3 around room temperature

Kawachi

Miyake

et al. 2017

Phys. Rev. Materials

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“…16 This spiral spin structure, which can be suppressed by doping, 17 leads to a cancellation of the macroscopic magnetization and also inhibits the observation of the linear ME effect. 18 However, significant magnetizations ͑between 0.1 B and 1 B per Fe͒, 2,19 as well as a strong ME coupling, 2 have been reported recently in high-quality epitaxial thin films. This suggests that the spiral spin structure is also suppressed in thin films, perhaps due to epitaxial constraints or enhanced anisotropy.…”

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Weak ferromagnetism and magnetoelectric coupling in bismuth ferrite

2005

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We analyze the coupling between the ferroelectric and magnetic order parameters in the magnetoelectric multiferroic BiFeO 3 using density functional theory within the local spin density approximation ͑LSDA͒ and the LSDA+ U method. We show that weak ferromagnetism of the Dzyaloshinskii-Moriya type occurs in this material, and we analyze the coupling between the resulting magnetization and the structural distortions. We explore the possibility of electric-field-induced magnetization reversal and show that, although it is unlikely to be realized in BiFeO 3 , it is not in general impossible. Finally, we outline the conditions that must be fulfilled to achieve switching of the magnetization using an electric field. There has been increasing recent interest in magnetoelectric multiferroics, 1-5 which are materials that show spontaneous magnetic and electric ordering in the same phase. In addition to the fascinating physics resulting from the independent existence of two or more ferroic order parameters in one material, 6 the coupling between magnetic and electric degrees of freedom gives rise to additional phenomena. The linear and quadratic magnetoelectric ͑ME͒ effects, in which a magnetization linear or quadratic in the applied field strength is induced by an electric field ͑or an electric polarization is induced by a magnetic field͒, are already well established. 5 Recently, more complex coupling scenarios have been investigated. Examples are the coupling of the antiferromagnetic and ferroelectric domains in hexagonal YMnO 3 , 1 or the large magnetocapacitance near the ferromagnetic Curie temperature in ferroelectric BiMnO 3 . 3 Especially interesting are scenarios where the direction of the magnetization or electric polarization can be modified by an electric or magnetic field, respectively. Such a coupling would open up entirely new possibilities in data storage technologies, such as ferroelectric memory elements that could be read out nondestructively via the accompanying magnetization. Some progress has been made in this direction. Recently, the small ͑0.08 C/cm 2 ͒ electric polarization in perovskite TbMnO 3 was rotated by 90°using a magnetic field at low temperatures ͑ϳ10-20 K͒. 4 Conversely, early work on nickel-iodine boracite 7 showed that, below ϳ60 K, reversal of the spontaneous electric polarization rotates the magnetization by 90°, indicating that the axis of the magnetization, but not its sense, can be controlled by an electric field. In fact, it was believed 8,9 that electric-field-induced 180°switching of the magnetization should be impossible, because a reversal of the magnetization corresponds to the operation of time inversion, whereas the electric field is invariant under this operation. In this work we show that such behavior is not generally impossible by using multiferroic bismuth ferrite, BiFeO 3 , as a test case to analyze the coupling between magnetism and ferroelectricity.BiFeO 3 has long been known to be, in its bulk form, an antiferromagnetic, ferroelectric multiferroic, 10,11 with anti...

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“…1 The linear magnetoelectric effect has been reported in bulk BiFeO 3 after breaking the modulated magnetic structure in the presence of high external magnetic field. 7,8 It has been suggested that chemical substitutions may also suppress the cycloidal spin structure. [9][10][11] The observation of an anomaly in the temperature dependence of dielectric constant around the magnetic transition temperature is often taken as an evidence for magnetoelectric coupling.…”

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Unambiguous evidence for magnetoelectric coupling of multiferroic origin in 0.73BiFeO3–0.27PbTiO3

Bhattacharjee

Pandey

Kotnala

et al. 2009

Applied Physics Letters

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Magnetization, frequency dependent dielectric, and structural studies on 0.73BiFeO 3 -0.27PbTiO 3 in the temperature range from 300 to 600 K reveal anomalies in the unit cell parameters and the intrinsic value of the dielectric constant, free from space charge contributions, at the antiferromagnetic transition temperature ͑T N ͒. Our results provide unambiguous confirmation of magnetoelectric coupling of multiferroic origin at T N and evidence for monoclinic distortion of the ferroelectric phase. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3068000͔ Bismuth based transition metal oxides ͑BiBO 3 ͒ and their solid solutions with other perovskites are known for their important multiferroic properties ͑see the recent reviews͒ [1][2][3] where the ferroelectricity arises due to the 6s lone pair chemistry of Bi +3 , while the magnetic order results from the Fe/ Mn/Cr ions occupying the B site. Of these compounds, BiFeO 3 is of special interest as its ferroelectric and magnetic transition temperatures are located well above the room temperature, raising possibilities of room temperature multiferroic devices. 1-3 Bulk BiFeO 3 shows a rhombohedrally distorted perovskite structure in the R3c space group with a ferroelectric transition temperature T C of ϳ1103 K ͑Ref. 4͒ and G-type antiferromagnetic ͑AFM͒ spin configuration with an incommensurate cycloidal spin structure 5 with a magnetic T N ϳ 643 K. 6 The long period modulated magnetic structure leads to the cancellation of net macroscopic magnetization and hence the absence of linear magnetoelectric coupling. 1 The linear magnetoelectric effect has been reported in bulk BiFeO 3 after breaking the modulated magnetic structure in the presence of high external magnetic field. 7,8 It has been suggested that chemical substitutions may also suppress the cycloidal spin structure. [9][10][11] The observation of an anomaly in the temperature dependence of dielectric constant around the magnetic transition temperature is often taken as an evidence for magnetoelectric coupling. 12,13 However, a dielectric anomaly at the magnetic transition temperature can also result from the magnetoresistance effects in granular systems 14 because of the large difference in the resistivities of the grains and grain boundaries. For an unambiguous confirmation of multiferroic coupling, it is therefore essential to demonstrate that the observed dielectric anomaly at the magnetic transition temperature is not due to the magnetoresistance at various interfaces such as grain boundaries. It should also be supported by other auxiliary evidence such as magnetoelastic coupling in the bulk phase through structural studies. 11 Here, we present the results of magnetization, dielectric, and structural studies as a function of temperature on 0.73BiFeO 3 -0.27PbTiO 3 ͑BF-0.27PT͒ ceramics, which reveal monoclinic distortion of the ferroelectric phase and intrinsic coupling between the AFM and ferroelectric order parameters. The particular composition ͑x = 0.27͒ that we have investigated is of special in...

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Magnetic-field-induced toroidal moment in the magnetoelectric Cr2O3

Cited by 126 publications

References 3 publications

Successive field-induced transitions in BiFeO3 around room temperature

Successive field-induced transitions in BiFeO3 around room temperature

Weak ferromagnetism and magnetoelectric coupling in bismuth ferrite

Unambiguous evidence for magnetoelectric coupling of multiferroic origin in 0.73BiFeO3–0.27PbTiO3

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