The compression behavior of delafossite compound CuCrO2 has been investigated by in-situ x-ray diffraction and Raman spectroscopic measurements upto 23.2 and 34 GPa respectively. X-ray diffraction data shows the stability of ambient rhombohedral structure upto ~ 23 GPa. Material shows large anisotropy in axial compression with c-axis compressibility, c= 1.2610-3(1) GPa-1 and a-axis compressibility, a= 8.9010-3(6) GPa-1. Our XRD data shows an irreversible broadening of diffraction peaks. Pressure volume data when fitted to 3rd order Birch-Murnaghan equation of state gives the value of bulk modulus, B0 = 156.7(2.8) GPa with its pressure derivative, B0' as 5.3(0.5). All the observed vibrational modes in Raman measurements show hardening with pressure. Appearance of a new mode at ~24 GPa indicates the structural phase transition in the compound. Our XRD and Raman results indicate that CuCrO2 may be transforming to an ordered rocksalt type structure under compression.
Comprehensive vibrational studies on the multiferroic-to-normal-ferromagnetic crossover in isostructural Ni3-xCoxV2O8 (NCVO, x = 0 - 3.0) are performed using Raman scattering spectroscopy. The systematically red-shifted phonon modes are discussed in terms of the mode Grüneisen parameters, and are interpreted as a chemical pressure effect. In addition, we present evidence that the local symmetry is broken in the multiferroic phase.
We report the first magnetic-field-dependent Raman scattering studies on Pb(Zr,Ti)O3-CoFe2O4 bilayer multiferroic system. The phonon frequencies of the nano-bilayers obviously change with magnetic field, which is absent in the single Pb(Zr,Ti)O3 films. The magnetostriction of the CoFe2O4 layer generates stress mechanically transferred to the Pb(Zr,Ti)O3 layer, resulting in the mode changes. The observed magnetic-field-induced softening of the soft mode in the Pb(Zr,Ti)O3 layer bears a striking resemblance to direct magnetoelectric output in the bilayers, providing evidence for stress-mediated …
We report a Raman scattering investigation of columnar BiFeO3-CoFe2O4 (BFO-CFO) epitaxial thin film nanostructures, where BFO pillars are embedded in a CFO matrix. The feasibility of a strain analysis is illustrated through an investigation of two nanostructures with different BFO-CFO ratios. We show that the CFO matrix presents the same strain state in both nanostructures, while the strain state of the BFO pillars depends on the BFO/CFO ratio with an increasing tensile strain along the out-of-plane direction with decreasing BFO content. Our results demonstrate that Raman scattering allows mon…
Low energy excitations in the multiferroic material TbMnO3 have been investigated by Raman spectroscopy. Our observations reveal the existence of two peaks at 30 cm-1 and 60 cm-1. They are observed in the cycloidal phase below the Curie temperature but not in the sinusoidal phase, suggesting their magnetoelectric origin. While the peak energies coincide with the frequencies of electromagnons measured previously by transmission spectroscopy, they show surprisingly different selection rules, with the 30 cm-1 excitation enhanced by the electric field of light along the spontaneous polarization. T…
The multiferroic manganese tungstate (MnWO4) has been studied by high-pressure Raman spectroscopy at room temperature under quasi-hydrostatic conditions up to 39.3 GPa. The low-pressure wolframite phase undergoes a phase transition at 25.7 GPa, a pressure around 8 GPa higher than that found in previous works which used less hydrostatic pressure-transmitting media. The pressure dependence of the Raman active modes of both the low- and high-pressure phases are reported and discussed comparing with the results available in the literature for MnWO4 and related wolframites. A gradual pressure-induc…
Raman study on a select few orthochromites, RCrO$_3$ (R = Y, Lu, Gd, Eu and Sm) shows that the phonon behavior at TN in compounds with magnetic R-ion (Gd and Sm) is remarkably different from that of non-magnetic R-ion (Y, Lu and Eu). While anomalies in most of the observed phonon frequencies in all these compounds may result from the distortion of CrO$_6$ octahedra due to size effect and magnetostriction arising from Cr-ordering, the anomalous behavior of their linewidths observed at TN for the compounds with only magnetic R-ion suggests spin-phonon coupling. The presence of spin-phonon coupli…
In this paper we investigated the influence of the rare-earth ionic radii on the spin-phonon coupling in RE2NiMnO6 double perovskites by Raman spectroscopy. Spin-phonon in dense Nd2NiMnO6 and Gd2NiMnO6 ceramics were investigated by Raman spectroscopy at low temperatures. The magnitude of the coupling observed in comparison with other isostructural compounds shows that it is not influenced by the rare-earth ionic radius, as well as the deviation of the position of the stretching phonon in the ferromagnetic phase with relation to the anharmonic contributions follows a power law.
Ultrasonic velocity measurements on the magnetoelectric multiferroic compound CuFeO2 reveal that the antiferromagnetic transition observed at TN1 = 14 K might be induced by an R-3m -> C2/m pseudoproper ferroelastic transition (G. Quirion, M. J. Tagore, M. L. Plumer, O. A. Petrenko, Phys. Rev. B 77, 094111 (2008)). In that case, the group theory states that the order parameter associated with the structural transition must belong to a two dimensional irreducible representation Eg (x^2 - y^2, xy). Since this type of transition can be driven by a Raman Eg mode, we performed Raman scattering measu…
Recently, CuO has been proposed as a potential multiferroic material with high transition temperature. Competing models based on spin current and ionic displacements are invoked to explain ferroelectricity in CuO. The theoretical model predicting ionic displacement suggested that the shift in ions is essentially along b-axis with very small amplitude (~10-5 Å). Experimentally detecting displacements of such a small amplitude in a particular direction is extremely challenging. Through our detailed polarized Raman spectroscopy study on epitaxial film of CuO, we have validated the theoretical stu…
The present work reports the preparation of polycrystalline multiferroic $GdFeO_3$ (GdFO) and characterization with x-ray diffraction (XRD), magnetization, temperature dependent Raman spectroscopy, temperature and magnetic field dependent $^{57}Fe$ M$\ddot{o}$ssbauer spectroscopy measurements. The sample is found to be phase pure from Rietveld refinement of XRD pattern. The M$\ddot{o}$ssbauer spectra measured in the presence of external magnetic field show the signatures of field induced spin reorientation transition, which are corroborated by magnetization measurements. From the temperature d…
We have carried out a detailed experimental investigation on CuO using dielectric constant, ac resistance, Raman spectroscopy and X-ray diffraction measurements at high pressures and room temperature. Both dielectric constant and dielectric loss show an anomalous peak in the pressure range 3.4-4 GPa indicating a ferroelectric transition. Raman studies show anomalous behaviour of the Ag mode with a slope change in the mode frequency and a minimum in the mode FWHM at 3.4 GPa indicating a strong spin phonon coupling along [1 0 -1] direction. A step like behaviour in the intensity of the Ag mode i…
Multiferroics possess two or more switchable states such as polarization, magnetization, etc. Phonon excitations in multiferroic phase are strongly modified by magnetoelectric coupling, spin-phonon coupling, and anharmonic phonon-phonon interactions. Here, we have investigated the correlation between phonons and multiferroic order parameters in hexagonal BaMO3: M = Ti1-x(Mn/Fe)x systems using powder x-ray diffraction (PXRD), Raman spectroscopic, and magnetic measurements. The structural transformation from a polar tetragonal to a non-polar 6H-type hexagonal phase is observed as a function of d…
We used Raman and terahertz spectroscopies to investigate lattice and magnetic excitations and their cross-coupling in the hexagonal YMnO3 multiferroic. Two phonon modes are strongly affected by the magnetic order. Magnon excitations have been identified thanks to comparison with neutron measurements and spin wave calculations but no electromagnon has been observed. In addition, we evidenced two additional Raman active peaks. We have compared this observation with the anti-crossing between magnon and acoustic phonon branches measured by neutron. These optical measurements underly the unusual s…
We report a detailed high-temperature powder neutron diffraction investigation of the structural behavior of the multiferroic GaFeO3 between 296 and 1368 K. Temperature dependent neutron diffraction patterns do not show any appreciable change either in intensity or appearance/disappearance of the observed peaks upto 1368 K, ruling out any structural transition in the entire temperature range. The lattice parameters and volume exhibit normal thermal expansion behaviour, indicating the absence of any structural changes with increasing temperature. The origin of the magnetoelectric couplings and …
Raman scattering measurements on BiFeO3 single crystals show an important coupling between the magnetic order and lattice vibrations. The temperature evolution of phonons shows that the lowest energy E and A1 phonon modes are coupled to the spin order up to the Neel temperature. Furthermore, low temperature anomalies associated with the spin re-orientation are observed simultaneously in both the E phonon and the magnon. These results suggest that magnetostriction plays an important role in BiFeO3.
Multiferroic bismuth ferrite (BiFeO3) thin films were prepared by pulsed laser deposition (PLD) technique. Electronic structures of the film have been studied by in situ photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS). Both the Fe 2p PES and XAS spectra show that Fe ion is formally in +3 valence state. The Fe 2p and O K edge XAS spectra indicate that the oxygen octahedral crystal ligand field splits the unoccupied Fe 3d state to t2g and eg states. Valence band Fe 2p-3d resonant photoemission results indicate that hybridization between Fe 3d and O 2p plays important rol…
High-pressure phase of boron oxide, orthorhombic \b{eta}-B2O3, has been studied in situ by synchrotron X-ray diffraction to 22 GPa and Raman scattering to 46 GPa at room temperature. The bulk modulus of \b{eta}-B2O3 has been found to be 169(3) GPa that is in good agreement with our ab initio calculations. Raman and IR spectra of \b{eta}-B2O3 have been measured at ambient pressure, all experimentally observed bands have been attributed to the theoretically calculated ones, and the mode assignment has been performed. Based on the data on Raman shift as a function of pressure, combined with equat…
The unique properties of graphene offer immense opportunities for applications to many scientific fields, as well as societal needs, beyond our present imagination. One of the important features of graphene is the relatively simple tunability of its electronic structure, an asset which extends the usability of graphene even further beyond present experience. A direct injection of charge carriers into the conduction or valence bands, i.e., doping, represents a viable way of shifting the Fermi level. In particular, the electrochemical doping should be the method of choice, when higher doping lev…
In this letter, we report that the special coupling between Dirac fermion and lattice vibrations, in other words, electron-phonon coupling (EPC), in silicene layers on Ag(111) surface was probed by an in-situ Raman spectroscopy. We find the EPC is significantly modulated due to tensile strain, which results from the lattice mismatch between silicene and the substrate, and the charge doping from the substrate. The special phonon modes corresponding to two-dimensional electron gas scattering at edge sites in the silicene were identified. Detecting relationship between EPC and Dirac fermion throu…
Ferroelectric domain nucleation and growth in multiferroic BiFeO3 films is observed directly by applying a local electric field with a conductive tip inside a scanning transmission electron microscope. The nucleation and growth of a ferroelastic domain and its interaction with pre-existing 71^{\circ} domain walls are observed and compared with the results of phase-field modeling. In particular, a preferential nucleation site and direction-dependent pinning of domain walls is observed due to slow kinetics of metastable switching in the sample without a bottom electrode. These in-situ spatially-…
Improvement of the photovoltaic efficiency (from 1.2% to 3%) via exposure of organic poly(3-hexylthiophene) (P3HT) + phenyl-C61-butyric acid methyl ester (PCBM) devices to solvent vapor at room temperature is reported. In situ photoluminescence (PL) and Raman spectroscopies, in conjunction with optical absorption data, have been used to provide insight into the nanoscale morphological changes occurring during solvent vapor annealing. We found that in P3HT:PCBM, suppression of PL and the decrease in line-width of the 1442 cm-1 P3HT Raman peak are accompanied by strong modifications in the optic…
Cubic boron phosphide BP has been studied in situ by X-ray diffraction and Raman scattering up to 55 GPa at 300 K in a diamond anvil cell. The bulk modulus of B0 = 174(2) GPa has been established, which is in excellent agreement with our ab initio calculations. The data on Raman shift as a function of pressure, combined with equation-of-state data, allowed us to estimate the Grüneisen parameters of the TO and LO modes of zinc-blende structure, γGTO = 1.16 and γGLO = 1.04, just like in the case of other AIIIBV diamond-like phases, for which γGTO > γGLO = 1. We also established that the pressure…
Controlling material properties by modulating the crystalline structure has been attempted using various techniques, e.g., hydrostatic pressure, chemical pressure, and epitaxy. These techniques succeed to improve properties and achieve desired functionalities by changing the unit cell in all dimensions. In order to obtain a more detailed understanding on the relation between the crystal lattice and material properties, it is desirable to investigate the influence of a smaller number of parameters. Here, we utilize the combination of chemical pressure and epitaxy to modify a single lattice para…
The effect of pressure on the Raman spectrum of PbWO4 has been investigated up to 48 GPa in a diamond-anvil cell using neon as pressure-transmitting medium. Changes are detected in the Raman spectrum at 6.8 GPa as a consequence of a structural phase transition from the tetragonal scheelite structure to the monoclinic PbWO4-III structure. Two additional phase transitions are detected at 15.5 and 21.2 GPa to the previously unknown crystalline phases IV and V. The last one remains stable up to 43.3 GPa. At 47.7 GPa all Raman modes disappear, which could be caused by a pressure-induced amorphizati…
Type-II multiferroic materials, in which ferroelectric polarization is induced by inversion non-symmetric magnetic order, promise new and highly efficient multifunctional applications based on the mutual control of magnetic and electric properties. Although this phenomenon has to date been limited to low temperatures, here we report a giant pressure-dependence of the multiferroic critical temperature in CuBr$_2$. At 4.5 GPa, $T_\mathrm{C}$ is enhanced from 73.5 to 162 K, to our knowledge the highest value yet reported for a non-oxide type-II multiferroic. This growth shows no sign of saturatin…
The two-dimensional silicon allotrope, silicene, could spur the development of new and original concepts in Si-based nanotechnology. Up to now silicene can only be epitaxially synthesized on a supporting substrate such as Ag(111). Even though the structural and electronic properties of these epitaxial silicene layers have been intensively studied, very little is known about its vibrational characteristics. Here, we present a detailed study of epitaxial silicene on Ag(111) using \textit{in situ} Raman spectroscopy, which is one of the most extensively employed experimental techniques to charact…
We report, for the first time, a comprehensive study involving in situ Raman spectroscopy supported by quantum mechanical calculations to exactly monitor the covalent binding to graphene with unprecedented precision. As a model reaction we have chosen the hydrogenation of reduced graphite ($KC_8$) with $H_2O$ and compared it with the corresponding exposure to $H_2$ and $O_2$. The early stages of graphene hydrogenation are accompanied by the evolution of a series of so far undiscovered D-bands ($D_1$-$D_5$). Using quantum mechanical calculations, we were able to unambiguously assign these bands…
Understanding the polarization switching mechanisms at play in ferroelectric materials is crucial for their exploitation in electronic devices. The conventional centrosymmetric reference structure-based mechanism which accounts for ferroelectricity in most of the usual displacive ferroelectric materials is too energy-demanding for some newly diagnosed ferroelectric materials such as the Ga2-xFexO3 (0.8 < x < 1.4) compounds. Some alternative theoretical propositions have been made and need experimental confirmation. A dual-scale electron microscopy study is performed on thin films of the Ga0.6F…
Study of amorphous alumina coatings for next-generation nuclear reactors: hightemperature in-situ and post-mortem Raman spectroscopy and X-ray diffraction
MnCr2O4 that exhibits spin frustration and complex spiral spin order is of great interest from both fundamental as well as application-oriented perspectives. Unlike CoCr2O4 whose ground state presents the coexistence of commensurate spiral spin order (CSSO) and ferroelectric order, MnCr2O4 shows no multiferroicity. One reason is that the spiral spin order is highly sensitive to the oxygen concentration in MnCr2O4. Here, we have successfully grown high-quality single-crystalline MnCr2O4 by the chemical vapor transport method. We observe a new first-order magnetic transition from the incommensur…
Nanostructured carbon films produced by supersonic cluster beam deposition have been studied by in situ Raman spectroscopy. Raman spectra show the formation of a sp2 solid with a very large fraction of sp-coordinated carbyne species showing a long-term stability under ultra high vacuum. Distinct Raman contribution from polyyne and cumulene species have been observed. The long-term stability and the behavior of carbyne-rich films under different gas exposure have been characterized showing different evolution for different sp configurations. Our experiments confirm theoretical predictions and d…
Ultra-high vacuum Raman platform for in situ characterization of graphene nanoribbons
Department of Information Technology and Electrical Engineering, ETH Zürich - Swiss Federal Institute of Technology Zürich（苏黎世联邦理工学院信息与电气工程系）；Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院）；Max Planck Institute for Polymer Research（马克斯·普朗克聚合物研究所）；Faculty of Chemistry and Food Chemistry & Center for Advanced Electronics Dresden, TUD - Dresden University of Technology（德累斯顿工业大学化学与食品化学学院及先进电子中心）；Max Planck Institute of Microstructure Physics（马克斯·普朗克微观结构物理研究所）
The interaction of double wall carbon nanotubes (DWCNTs) and the conducting polymer poly(3,4-ethylenedioxythiphene/polystyrenesulfonate (PEDOT/PSS) was studied by in-situ Raman spectroelectrochemistry. The mixing of DWCNTs with PEDOT/PSS caused a partial doping of the outer tube of DWCNTs, which was indicated by the relative change of the Raman intensity of the DWCNTs features. On the other hand, the bands corresponding to inner tubes of DWCNTs and to the polymer were almost untouched by assembling both species into a composite. The in situ Raman spectroelectrochemical experiments have shown t…
The interaction of coexisting structural instabilities in multiferroic materials gives rise to intriguing coupling phenomena and extraordinarily rich phase diagrams, both in bulk materials and strained thin films. Here we investigate the multiferroic BiMnO3 with its peculiar 6s2 electrons and four interacting mechanisms: electric polarity, octahedra tilts, magnetism, and cooperative Jahn-Teller distortion. We have probed structural transitions under high pressure by synchrotron x-ray diffraction and Raman spectroscopy up to 60 GPa. We show that BiMnO3 displays under pressure a rich sequence of…
Spectroscopic modes provide the most sensitive probe of the very weak interactions responsible for the properties of the long-wavelength cycloid in the multiferroic phase of \BF below $\TN \approx 640$ K. Three of the four modes measured by THz and Raman spectroscopies were recently identified using a simple microscopic model. While a Dzyaloshinskii-Moriya (DM) interaction $D$ along $[-1,2,-1]$ induces the cycloid with wavevector $(2π/a)(0.5+δ, 0.5, 0.5-δ)$ ($δ\approx 0.0045$), easy-axis anisotropy $K$ along the $[1,1,1]$ direction of the electric polarization ${\bf P}$ induces higher harmonic…
A new experimental approach for in-situ Raman spectroscopy of the electrode | solid electrolyte interfaces in controlled atmospheres, based on the use of optically transparent single-crystal membranes of stabilized cubic zirconia, has been proposed and validated. This technique makes it possible to directly access the electrochemical reaction zone in SOFCs by passing the laser beam through single-crystal electrolyte onto the interface, in combination with simultaneous electrochemical measurements. The case study centered on the analysis of NiO reduction in standard cermet anodes under open-cir…
Mixtures containing different weight ratios of single wall carbon nanotubes (SWCNT) and double wall carbon nanotubes (DWCNT) were prepared and studied by in-situ Raman spectroelectrochemistry. Two components of the G-prime mode in the Raman spectra, which can be resolved at high electrode potentials, were assigned to the signals from inner tubes of DWCNT and outer tubes of DWCNT together with SWCNT. The dependence of the ratios of these two components of the G-prime mode on the nominal amount of SWCNT and DWCNT in the samples was simulated so that the residual amount of SWCNT in the original D…
We study the kinetics of the H release from plasma-deposited hydrogenated amorphous carbon films under isothermal heating at 450, 500 and 600 {\degree}C for long times up to several days using in situ Raman microscopy. Four Raman parameters are analyzed. They allow the identification of different processes such as the carbon network reorganization and the H release from sp3 or sp2 carbon atoms and the corresponding timescales. Carbon reorganization with aromatization and loss of sp3 hybridization occurs first in 100 minutes at 500 {\degree}C. The final organization is similar at all investigat…
The Haldane spin-chain (S=1) insulating compound, Sm2BaNiO5, which has been proposed to order antiferromagnetically around (T_N=) 55 K, was investigated for its complex dielectric permittivity, magnetodielectric and pyrocurrent behavior as a function of temperature (T). In order to enable meaningful discussions, the results of ac and dc magnetizatioin and heat-capacity studies are also reported. We emphasize on the following findings: (i) There is a pyrocurrent peak near T_N, but it is shown not to arise from ferroelectricity, but possibly due to 'thermally stimulated depolarization current', …
Fluid dispersed two-dimensional (2D) composite materials with dynamically tunable functional properties have recently emerged as a novel highly promising class of optoelectronic materials, opening up new routes not only for the emerging field of metamaterials but also to chip-scale multifunctional metadevices. However, in-situ monitoring and detection of the dynamic ordering of 2D nanoparticles on chip and during the device operation is still a huge challenge. Here we introduce a novel approach for on-chip, in-situ Raman characterisation of 2D-fluid composite materials incorporated into Si pho…
Hexagonal LuFe2O4 is a promising charge-order (CO) driven multiferroic material with high charge and spin ordering temperatures. The coexisting charge and spin orders on Fe3+/Fe2+ sites result in novel magnetoelectric behaviors, but the coupling mechanism between the charge and spin orders remains elusive. Here, by tuning external pressure, we reveal three correlated spin-charge ordered phases in LuFe2O4: i) a centrosymmetric incommensurate three-dimensional CO with ferrimagnetism, ii) a non-centrosymmetric incommensurate quasi-two-dimensional CO with ferrimagnetism, and iii) a centrosymmetric…
The ferroelectric to paraelectric phase transition of multiferroic CaMnTi$_2$O$_6$ has been investigated at high pressures and ambient temperature by second harmonic generation (SHG), Raman spectroscopy, and powder and single-crystal x-ray diffraction. We have found that CaMnTi$_2$O$_6$ undergoes a pressure-induced structural phase transition ($P4_2mc \rightarrow P4_2/nmc$) at $\sim$7 GPa to the same paraelectric structure found at ambient pressure and $T_c$ = 630 K. The continuous linear decrease of the SHG intensity that disappears at 7 GPa and the existence of a Raman active mode at 244 cm$…
We present detailed multi frequency resonant Raman measurements of potassium graphite intercalation compounds (GICs). From a well controlled and consecutive in-situ intercalation and high temperature de-intercalation approach the response of each stage up to stage VI is identified. The positions of the G and 2D lines as a function of staging depend on the charge transfer from K to the graphite layers and on the lattice expansion. Ab-initio calculations of the density and the electronic band-structure demonstrate that most (but not all) of the transferred charge remains on the graphene sheets a…
We use Raman spectroscopy in tandem with transmission electron microscopy and DFT simulations to show that extreme (GPa) pressure converts the phase of silicon nanowires from cubic (Si-I) to hexagonal (Si-IV) while preserving the nanowire's cylindrical morphology. In situ Raman scattering of the TO mode demonstrates the high-pressure Si-I to Si-II phase transition near 9 GPa. Raman signal of the TO phonon shows a decrease in intensity in the range 9 to 14 GPa. Then, at 17 GPa, it is no longer detectable, indicating a second phase change (Si-II to Si-V) in the 14 to 17 GPa range. Recovery of ex…
The potential of silicon nanowires (SiNWs), (diameter < 10 nm) to transform into rigid bundle-like structures with distinct phonon confinement under high pressure (<= 15 GPa), instead of amorphising as per previous reports, is demonstrated using in-situ Raman spectroscopy. The newly observed splitting of the second order transverse optical (2TO) Raman mode into 2TO(L) and 2TO(W) phonon modes at >= 5 GPa establishes a highly anisotropic and mode-dependent pressure response of these SiNWs. Properties of the novel structures are superior compared to other nano-structured silicon and bulk-Si in te…
We present a fast and simple way to determine the erosion rate and absorption coefficient of hydrogenated amorphous carbon films exposed to a hydrogen atomic source based on ex-situ Raman micro-spectroscopy. Results are compared to ellipsometry measurement. The method is applied to films eroded at different temperatures. A maximum of the erosion rate is found at ~ 450 {\degree}C in agreement with previous results. This technique is suitable for future quantitative studies on the erosion of thin carbonaceous films, especially of interest for plasma wall interactions occurring in thermonuclear f…
We present a detailed in-situ Raman analysis of stage-1 KC8, CaC6, and LiC6 graphite intercalation compounds (GIC) to unravel their intrinsic finger print. Four main components were found between 1200 cm-1 and 1700 cm-1, and each of them were assigned to a corresponding vibrational mode. From a detailed line shape analysis of the intrinsic Fano-lines of the G- and D-line response we precisely determine the position (ωph), line width (Γph) and asymmetry (q) from each component. The comparison to the theoretical calculated line width and position of each component allow us to extract the electro…
The magnetoelectric coupling, i.e., cross-correlation between electric and magnetic orders, is a very desirable property to combine functionalities of materials for next-generation switchable devices. Multiferroics with spin-driven ferroelectricity presents such a mutual interaction concomitant with magneto- and electro-active excitations called electromagnons. TbMnO3 is a paradigmatic material in which two electromagnons have been observed in the cycloidal magnetic phase. However, their observation in TbMnO3 is restricted to the cycloidal spin phase and magnetic ground states that can support…
