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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Nonlinear Optics of Multiferroic Materials
摘要： Multiferroics, that is, materials with a coexistence of long-range magnetic and electric order have been attracting tremendous interest because of pronounced coupling effects between magnetic and electric properties that may be the basis for novel devices in which a magnetization is controlled by an electric voltage rather than by energy-intensive electric-current-driven magnetic fields. For monitoring as well as controlling the magnetoelectric coupling, it is essential to have simultaneous access to the magnetic and electric phase of a multiferroic. Only then, the spatial relation between the magnetic and electric domain structures and their response to external perturbations like applied magnetic or electric fields can be studied. Nonlinear optics is particularly well suited for this purpose. The simplest nonlinear optical process is second harmonic generation (SHG) (cid:650) doubling of the frequency of a light wave in a material. SHG is a very symmetry-sensitive process. Any reduction of the symmetry of the frequency-doubling medium can lead to new SHG contributions. Since all types of ferroic order reduce the point group symmetry, SHG can be used as background-free probe of the occurring order. In general, the magnetic and the electric order of a multiferroic change symmetry in different ways so that they are represented by different SHG contributions. These are readily separated by polarization filters so that SHG is an ideal tool to observe the coexistence and correlation between the ferroic phases and their domains in a single experiment. Polarization-dependent SHG spectroscopy and imaging experiments are therefore ideal for analysing the magnetoelectric correlation in a broad variety of multiferroic materials. Some of the most important achievements of nonlinearoptics on multiferroics are: (cid:120) Detection of a coupling between antiferromagnetic and ferroelectric order in hexagonal manganites that occurs in the domain walls rather than in the domains. The result anticipated the current interest in domain walls as functional oxide interfaces [1]. (cid:120) A coupling between magnetic and electric domains in TbMnO3 sustained even across a first-order (cid:120) phase transition [2]. Inversion of a multiferroic domain pattern: The direction of the magnetic or electric order parameter of a multiferroic is reversed across the entire sample, but the domain patterns such is retained [3]. (cid:120) Reversal of a multiferroic domain state without application of external DC fields, just by light [4]. (cid:120) In-situ tracking of the emergence of ferroic order in multiferroic oxide thin films by monitoring the formation of the ordered state by SHG during growth [5]. Optical access in all these experiments involves lasers emitting light pulses of either 100 fs or 5 ns. The laser light can be used to monitor the multiferroic order by nonlinear optics but also, prior to that, to manipulate the ordered state by with an intense pump light beam and analyse the ensuing dynamics. In view of the versatility of the optical access to multiferroics and the generality of the symmetry-based approach to the detection of ferroic phases, it is to be expected that the field of nonlinear optics on multiferroics will continue to develop at the highest speed.
关键词： magnetoelectric coupling,multiferroic materials,second harmonic generation,Nonlinear optics
更新于2025-09-11 14:15:04
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Thin Films with Checkerboard-Ordered Oxygen Vacancies and Low Magnetic Damping
摘要： The possibility of affecting the magnetic properties of a material by dielectric means, and vice versa, remains an attractive perspective for modern electronics and spintronics. Here, we report on epitaxial Bi(Fe0.5Mn0.5)O3 thin films with exceptionally low Gilbert damping and magnetoelectric coupling above room temperature (< 400 K). The ferromagnetic order, not observed in bulk, has been detected with a total magnetization of 0.44 μB/formula units with low Gilbert damping parameter (0.0034), both at room temperature. Additionally, a previously overlooked check-board ordering of oxygen vacancies is observed, providing insights on the magnetic and dielectric origin of the multifunctional properties of the films. Finally, intrinsic magnetodielectric behavior is observed as revealed by the variation of dielectric permittivity well above room temperature. These findings show the possibility of electric-field-controlled magnetic properties, in low Gilbert-damping-based spintronic devices, using single-phase multiferroic materials.
关键词： magnetodielectric,Gilbert damping,thin films,Bi(Fe0.5Mn0.5)O3,magnetoelectric coupling
更新于2025-09-11 14:15:04
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Modular approach to understanding and synthesis of metamaterials and metasurfaces
摘要： The vast majority of previously proposed metamaterials and metasurfaces are anisotropic or bianisotropic (exhibiting magnetoelectric coupling). Nevertheless, their anisotropy was not fully exploited as they were designed only for one or several specific illumination directions. In this talk, we propose a simple analytical approach to characterize properties of general bianisotropic meta-atoms for an arbitrary illumination. The approach is based on the qualitative decomposition of an arbitrary meta-atom into separate basic “modules” with elementary polarization properties. Such decomposition can be used for comprehensive characterization of previously designed structures as well as for synthesizing novel bianisotropic inclusions of arbitrary complexity and with desired response.
关键词： polarization properties,anisotropy,metamaterials,bianisotropic,metasurfaces,magnetoelectric coupling
更新于2025-09-10 09:29:36
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Electrical-poling-induced strain effect in Pb(Fe0.534W0.066Nb0.4)O3
摘要： The electrical control of magnetism is a potential technique for low-energy-consuming spintronic devices. In this work, Pb(Fe0.534W0.066Nb0.4)O3 (PFWN), a known magnetoelectric-multiferroic compound, is poled using dc electric field to study the impact of induced strain on the vibrational modes and magnetism using Raman spectroscopy and magnetic susceptibility measurements, respectively. PFWN exhibits ferroelectric phase transition at TC * 300 K and antiferromagnetic ordering around TN * 187 K coinciding with an anomaly in the temperature-dependent Raman studies, indicating spin-phonon coupling. The observed changes in Raman modes and magnetization of electrically poled PFWN indicate strong converse magnetoelectric coupling effect. The electric-field-induced strain induces tilting of the FeO6 octahedra, which alters hybridization between Fe 3d and O and 2p orbitals, respectively. We present results of our studies on electric poling of PFWN in the light of current interest in the magnetic switching applications of spintronic materials.
关键词： Structure,Vibrational,Multiferroics and magnetoelectric coupling,Magnetism
更新于2025-09-10 09:29:36
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High magnetoelectric coupling in Si-integrated AlN/NiMnIn thin film double layers at room temperature
摘要： The current study explores the presence of strong magnetoelectric (ME) coupling in a sputtered deposited NiMnIn/aluminum nitride (AlN) heterostructure on an Si substrate. The X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy results confirm the formation of a pure AlN wurtzite phase in the ME heterostructure. The magnetization vs temperature measurement shows the presence of the martensite transformation region of the NiMnIn/AlN heterostructure. The magnetic measurements exhibit the room temperature ferromagnetic nature of the NiMnIn/AlN heterostructure. The NiMnIn/AlN ME heterostructure was found to have a high ME coupling coefficient of (cid:2)99.2 V/cm Oe at Hdc ? 300 Oe. The induced ME coupling coefficient shows a linear dependency on Hac up to 8 Oe.
关键词： room temperature,Si-integrated,thin film,magnetoelectric coupling,AlN/NiMnIn
更新于2025-09-04 15:30:14