Enhanced Directional Dichroism of Terahertz Light in Resonance with Magnetic Excitations of the Multiferroic<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>Ba</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>CoGe</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>7</mml:mn></mml:msub></mml:math>Oxide Compound

Kézsmárki, I.; Kida, N.; Murakawa, H.; Bordács, S.; Onose, Y.; Tokura, Y.

doi:10.1103/physrevlett.106.057403

Cited by 182 publications

(196 citation statements)

References 22 publications

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“…High quality single crystals of Ba 2 CoGe 2 O 7 were grown by floating-zone technique and characterized in previous studies [9,11,13,18]. SNP measurements were performed at 4 K with a Cryopad on the polarized single-crystal diffractometer POLI@HEiDi at the hot source of the FRM II reactor in Garching, Germany [19,20].…”

Section: Methodsmentioning

confidence: 99%

“…The field dependence of the ferroelectric polarization in Ba 2 CoGe 2 O 7 was reproduced by ab initio calculations [5], however, the magnitude of the predicted polarization was considerably smaller than the experimental value. The spin-wave excitation spectrum of this material together with the strong optical magnetoelectric effect exhibited by these magnon modes are captured by a microscopic spin Hamiltonian where single-ion anisotropy dominates over magnetic exchange interaction [6][7][8][9][10]. Nevertheless, some of the magnon modes appearing in intermediate magnetic fields (5 T < B < 14 T) remained unexplained by the theory.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of two-dimensional antiferromagnetism with temperature and magnetic field in multiferroicBa2CoGe2O7

et al. 2014

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We report on spherical neutron polarimetry and unpolarized neutron diffraction in zero magnetic field as well as flipping ratio and static magnetization measurements in high magnetic fields on the multiferroic square lattice antiferromagnet Ba 2 CoGe 2 O 7 . We found that in zero magnetic field the magnetic space group is Cm m2 with sublattice magnetization parallel to the [100] axis of this orthorhombic setting. The spin canting has been found to be smaller than 0.2 • in the ground state. This assignment is in agreement with the field-induced changes of the magnetic domain structure below 40 mT as resolved by spherical neutron polarimetry. The magnitude of the ordered moment has been precisely determined. Above the magnetic ordering temperature short-range magnetic fluctuations are observed. Based on the high-field magnetization data, we refined the parameters of the recently proposed microscopic spin model describing the multiferroic phase of Ba 2 CoGe 2 O 7 .

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evolution of two-dimensional antiferromagnetism with temperature and magnetic field in multiferroicBa2CoGe2O7

et al. 2014

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“…Pioneering works [9,10] [51,52], and Ba 2 CoGeO 7 [53]. These investigations revealed new excitations in THz time domain region and posed a set of questions.…”

Section: Evidences For Electromagnons In Multiferroicsmentioning

confidence: 99%

Electrically active magnetic excitations in antiferromagnets (Review Article)

Krivoruchko

2012

Low Temperature Physics

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The magnetic resonance operation by electric field is highly nontrivial but the most demanding function in the future spin-electronics. Recently observed in a variety of multiferroics materials named the collective electrically active magnetic excitations, frequently referred to as "electromagnons", reveal a possible way to implement such a function. Experimental advances in terahertz spectroscopy of electromagnons in multiferroics as well as related theoretical models are reviewed. The earlier theoretical works, where the existence of electric-dipole active magnetic excitations in antiferro-and ferrimagnets with collinear spin structure has been predicted, are also discussed. Multi-sublattice magnets with electrically active magnetic excitations at room temperature give a direct possibility to transform one type of excitation into another in a terahertz time-domain. This is of crucial importance for the magnon-based spintronics as only the short-wavelength exchange magnons allow the signal processing on the nanoscale distance.

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“…The ME dual of electromagnons, that is magneto-active excitations of the lattice, have also been recently reported [9]. This type of hybrid excitations enable additional optical functionalities such as directional light switching and quadrochroism [10] that open new perspectives in photonics and magnonics [11].…”

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confidence: 99%

Magneto- to Electroactive Transmutation of Spin Waves inErMnO3

et al. 2014

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The low energy dynamical properties of the multiferroic hexagonal perovskite ErMnO3 have been studied by inelastic neutron scattering as well as terahertz and far infrared spectroscopies on synchrotron source. From these complementary techniques, we have determined the magnon and crystal field spectra and identified a zone center magnon only excitable by the electric field of an electromagnetic wave. Using comparison with the isostructural YMnO3 compound and crystal field calculations, we propose that this dynamical magnetoelectric process is due to the hybridization of a magnon with an electro-active crystal field transition. The term magnetoelectric (ME) makes reference to a variety of phenomena in which electric dipoles and magnetic moments are mutually linked [1]. ME processes attract a considerable research interest, largely driven by their potential use in future information technologies [1, 2] and, more recently, by their interpretation in terms of exotic magnetic and ME monopoles [3]. A ME process that is particularly striking is the electric-charge dressing of spin-waves that gives rise to electrically active magnons (or electromagnons) [4].This dynamical ME effect has been most clearly demonstrated in multiferroic materials such as Several microscopic mechanisms have been identified behind the ME character of these hybrid excitations. In essence, they all trace back to the specific couplings between spins and the deformable lattice that can produce ferroelectricity. In orthorhombic RMnO 3 , for example, both the so-called inverse Dzyaloshinksii-Moriya and Heisenberg exchange mechanisms contribute to the static polarization [12] and also generate different electromagnons [5]. In hexagonal YMnO 3 , a phonon-magnon anticrossing has been observed revealing that lattice and spins are dynamically coupled in this system too [13,14]. However, the ME nature of this feature was not been proven and, to the best of our knowledge, no electromagnon has been reported so far in the other members of this family of prominent multiferroics [15][16][17]. In thisFIG. 1: Schematic illustration of ErMnO3 crystallographic and magnetic structure in the temperature range T N < T < TN where Mn magnetic moments are ordered at 120 • (a) and Er moments on the 4b site only are polarized in an antiferromagnetic arrangement (b). This multiferroic phase presents an electric polarisation P along the c-axis. The exchange interactions involved in the Mn magnetic order are also shown.Letter, we report on the presence of a new type of ME excitation in the hexagonal ErMnO 3 multiferroic compound. By means of complementary spectroscopic tools and the comparison with hexagonal YMnO 3 , we show evidence of the transmutation of a regular magnon to an electro-active excitation in ErMnO 3 . We ascribe this effect to a distinct hybridization mechanism between Mn 3+ spin-waves and crystal field (CF) excitations of the Er 3+ rare earth.In ErMnO 3 , the ferroelectric state occurs below T c = 833 K with a spontaneous polarization along the c-axis (pola...

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Enhanced Directional Dichroism of Terahertz Light in Resonance with Magnetic Excitations of the MultiferroicBa2CoGe2O7Oxide Compound

Cited by 182 publications

References 22 publications

Evolution of two-dimensional antiferromagnetism with temperature and magnetic field in multiferroicBa2CoGe2O7

Evolution of two-dimensional antiferromagnetism with temperature and magnetic field in multiferroicBa2CoGe2O7

Electrically active magnetic excitations in antiferromagnets (Review Article)

Magneto- to Electroactive Transmutation of Spin Waves inErMnO3

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