Multiferroic Compound Research Articles

Phase transition, structural and magnetic parameters of vanadium-substituted Bi0.9Sm0.1FeO3 multiferroic ceramics

ABSTRACT The inorganic multiferroic compounds Bi0.9Sm0.1Fe1 − x V x O3 (x = 0.0, 0.015, 0.03, and 0.045) were prepared by the solid-state reaction method. X-ray diffraction analysis confirmed the rhombohedral perovskite-like structure with minor traces of the impurity phases Bi2Fe4O9 and Bi25FeO40. The lattice parameters a and c, and the volume of the hexagonal unit cell were extracted from the X-ray diffraction data and found to increase as the V5+ content is increased. The average crystallite size was estimated to be in the range 380–415 Å. Fourier transform infrared spectroscopy confirmed the rhombohedral perovskite-like structure via the vibration bands of the octahedral FeO6 group observed between 410 and 570 cm−1. A differential scanning calorimeter was used to record the thermal scans which revealed that the compounds have undergone crystalline phase transitions at temperatures in the range 300–320°C. A 4.5% V + 5 substitution has shifted the transition peak by 20°C. The magnetic hysteresis loops taken at room temperature with a vibrating sample magnetometer revealed the ordinary ferromagnetic behavior. The V5+ substitution enhanced the remanent magnetization, but the magnetic coercivity was found to fluctuate around an average value of about 1000 Oe. The compound Bi0.9Sm0.1Fe0.955V0.045O3 exhibited the maximum remanent magnetization.

Augmentation of optical and magnetic characteristics at ambient temperature in bismuth ferrite-titanium (BiFe1–xTixO3) multiferroic compounds

A facile sol–gel approach was utilized to synthesis BiFe1-xTixO3 multiferroic ferrites, denoted as BFO-xTi (with x from 0.00 to 0.10). XRD analysis revealed that the undoped BFO ferrite exhibited a rhombohedral structure, and a transition from the rhombohedral phase to the pseudo-cubic phase occurred as the Ti content increased. The optical band gap increased from 2.00 eV to 2.23 eV with a Ti substitution at 0.10 mol. The magnetic properties exhibited a transition from antiferromagnetic to ferromagnetic phase due to the structural phase transition and super-exchange interaction between the 3d orbitals of Ti4+ and Fe3+/Fe2+ at the B-sites through oxygen vacacies. The sample with a 0.10 mol Ti substitution demonstrated the highest M s and M r values of 3.68 emu g−1 and 7.21 × 10–3 emu g−1, respectively. Overall, the results suggest that the BiFe1-xTixO3 multiferroic ferrites with optimal composition hold promise for use in magneto-optical devices.

Magnetoelectric Properties of Aurivillius-Layered Perovskites

In the present work, we have synthesized rare-earth ion modified Bi4−xRExTi2Fe0.7Co0.3O12−δ (RE = Dy, Sm, La) multiferroic compounds by the conventional solid-state route. Analysis of X-ray diffraction by Rietveld refinement confirmed the formation of a polycrystalline orthorhombic phase. The morphological features revealed a non-uniform, randomly oriented, plate-like grain structure. The peaks evident in the Raman spectra closely corresponded to those of orthorhombic Aurivillius phases. Dielectric studies and impedance measurements were carried out. Asymmetric complex impedance spectra suggested the relaxation of charge carriers belonging to the non-Debye type and controlled by a thermally activated process. Temperature-dependent AC conductivity data showed a change of slope in the vicinity of the phase transition temperature of both magnetic and electrical coupling natures. Based on the universal law and its exponent nature, one can suppose that the conduction process is governed by a small polaron hopping mechanism but significant distortion of TiO6 octahedral. The doping of the A-sites with rare-earth element ions and changes in the concentrations of Fe and Co ions located on the B-sites manifested themselves in saturated magnetic hysteresis loops, indicating competitive interactions between ferroelectric and canted antiferromagnetic spins. The magnetic order in the samples is attributed to pair-wise interactions between adjacent Fe3+–O–Fe3+, Co2+/3+–O–Co3+/2+, and Co2+/3+–O–Fe3+ ions or Dzyaloshinskii–Moriya interactions among magnetic ions in the adjacent sub-lattices. As a result, enhanced magnetoelectric coefficients of 42.4 mV/cm-Oe, 30.3 mV/cm-Oe, and 21.6 mV/cm-Oe for Bi4−xDyxTi2Fe0.7Co0.3O12−δ (DBTFC), Bi4−xLaxTi2Fe0.7Co0.3O12−δ (LBTFC), and Bi4−xSmxTi2Fe0.7Co0.3O12−δ (SBTFC), respectively, have been obtained at lower magnetic fields (<3 kOe). The strong coupling of the Aurivillius compounds observed in this study is beneficial to future multiferroic applications.

Enhancement of optical absorption in multiferroic 0.5PZT-0.5PFN thin films: Experiments and first-principles analysis

Multiferroic compounds have gained research attention in the field of ferroelectric photovoltaics due to the presence of transition-metal d states from magnetic ions, which tend to reduce the bandgap value. In this work, 0.5Pb(Zr0.52Ti0.48)O3–0.5Pb(Fe0.5Nb0.5)O3 [PZTFN0.5] thin films were synthesized using a sol-gel route to investigate the effect of iron doping on optical and multiferroic properties. For comparative analysis, the end-member compositions, Pb(Zr0.52Ti0.48)O3 [PZT] and Pb(Fe0.5Nb0.5)O3 [PFN], were also synthesized under identical conditions. Our results revealed that the incorporation of Fe3+ ions into the PZT lattice not only induces multiferroic behavior, but also effectively enhances the optical absorption of the material in the visible light region. Optical transitions at ∼3.0 eV (∼2.4 eV) and ∼2.7 eV (∼2.2 eV) for the direct (indirect) bandgap were determined for PZTFN0.5 and PFN, respectively, indicating that the absorption edges of the iron-containing films result more promising than PZT (direct Eg∼3.6 eV) for photovoltaic applications. Both PZTFN0.5 and PFN thin films exhibit multiferroic behavior at room temperature, with different electric and magnetic properties. While PZTFN0.5 presents saturated hysteresis loops with remanent polarization values around 10 μC/cm2 and magnetization of 1.6 emu/cm2, PFN displays significantly larger remanence (31 emu/cm2) but poorer ferroelectric properties due to the presence of leakage. Microscopic insights into the structural and electronic properties of the PZTFN0.5 solid solution were provided from first-principles calculations.

Pressure and chemical doping induced phase transition and phonon dynamics of multiferroic Bi5Ti3FeO15 ceramics

The external pressure and doping effect have been studied on the lattice structure of multiferroic Bi5Ti3−2xFe1+xNbxO15 (BTFNx) ceramics. Based on the x-ray diffraction and the Raman spectroscopic evidence, it is confirmed that the doping-induced lattice deformation is closely related to the concentrations of the Nb5+ and Fe3+ ions. The Bi5Ti3FeO15 (BTF) ceramic transits from orthorhombic (O, A21am) - O and tetragonal (T) - T (I4/mmm) with pressure, showing the intermediate phase coexistence at a wide pressure range of 4.5–14.8 GPa, while for BTFN0.6 ceramics, it is O (Fmm2) - O and T - T(I4/mmm) having the phase coexistence at 6–18 GPa. The ionic substitution, phase diagram and the evolution of phonon, lattice symmetry, and stability of BTFNx ceramics have been systematically observed and studied under the internal and external factors. Our work provides a comprehensive understanding of the structural and physical functionality for the development and optimization of multiferroic four-layer compounds BTF material systems.

Magnetic structure of a multiferroic compound: Cu2OCl2.

The Cu2OCl2 compound has been shown to be a high-temperature spin-driven multiferroic system, with a linear magneto-electric coupling. In this paper we propose a complete study of its magnetic structure. We derive the low energy magnetic Hamiltonian using ab initio multi-reference configuration interaction and the spin structure using Monte-Carlo simulations. Among the three magnetic structures proposed in the literature from different experimental results, our calculations support the incommensurate cycloid magnetic structure with a q⃑ = (qa,0,0) propagation vector. Using symmetry analysis, we show that all experimental results (polarization, magnetic order, magneto-electric coupling) can be accounted for in the Fd'd'2 magnetic space group (2-fold axis along c⃑).

Doping effect on magnetic properties of high-temperature multiferroic compound YBaCuFeO5

We have investigated the impurity effects on magnetic properties for the oxygen-deficiency ordered perovskite YBaCuFeO5, which has multiferroic phenomenon at TN2 = 319 K. The measurements of the magnetic susceptibility χ have been carried out for the polycrystalline samples of YBaCu1-xMxFeO5 (M = Ni, Mn, and Zn), where the Cu2+ spins (S = 1/2) are partially substituted by the nonmagnetic and magnetic ions. From anomalies of the temperature dependence of χ, the doping concentration dependences of the magnetic transition temperatures such as TN1 and TN2, were determined. With increasing the doping concentration for YBaCu1-xMxFeO5 (M = Ni, Mn, and Zn), the value of TN1 decreases, and that of TN2 increases, and two magnetic transitions become one at x = xc. In the doping region of x > xc, the magnetic behaviors of the magnetic ions doped systems are different from that of the nonmagnetic one. In particular, we found that two magnetic transitions newly appear for the Ni- and Mn-doped systems in the region of x > xc. Based on the obtained results, we discussed the physics of impurity effects on the magnetic transitions for the high-temperature multiferroic compound YBaCuFeO5.

Wolframite-type MnMoO4: Magnetization, sintering by Cool-SPS, and magnetodielectric effect

Dense ceramic samples of wolframite-type MnMoO4 (w-MnMoO4) have been prepared by Cool-SPS (Spark Plasma Sintering) for the first time with the goal of investigating the magnetic, dielectric, and magneto-electric properties of this thermally fragile polymorph of MnMoO4. Earlier studies found that w-MnMoO4 converts to the structurally different α-MnMoO4 phase if heated in air at 873 K, thus hindering fabrication of w-MnMoO4 ceramics by conventional high-temperature sintering. Unsintered powder samples, which were prepared via a hydrothermal method, and dense ceramics elaborated by Cool-SPS have the same magnetic properties. Magnetic susceptibilities display Curie-Weiss behaviour, χ = C/(T-θ), with effective moments for Mn2+ ion μeff ≈ 5.9 μB/Mn-atom and negative Weiss temperatures θ ≈ - 96 to - 98 K. Unlike the isostructural multiferroic compounds MnW1-xMoxO4 (0 ≤ x < 0.3) which exhibits at least two successive magnetic transitions below 15 K, w-MnMoO4 undergoes only one paramagnetic-to-antiferromagnetic transition at TN ≈ 32 K. The field-dependent magnetization at 2 K shows a spin-flop transition at μ0HSF ≈ 2 T. Capacitance and dielectric losses obtained for a ceramic between 2 and 300 K in zero field and in a field of 9 T reveal several weak anomalies. Dielectric anomalies are observed at the magnetic phase transition, suggesting a magnetoelectric coupling. Qualitatively different dielectric and magnetodielectric behaviours occur in α-MnMoO4 ceramics at low temperature.

Structural analysis and polarization study of CoCr2O4 nanoparticles

We present the room temperature polarization study of the multiferroic compound CoCr2O4. The co-existence of two elements (Co and Cr) in partially filled d-blocks makes these compounds exhibit a wide range of physical properties. The Cr3+ions almost invariably cover the octahedral (Oh) sites as the crystal field stabilization energy (CFSE) is more than 224 kJ mol −1. The chemical based Sol-gel self-combustion method has been used to successfully synthesize CoCr2O4 chromite. Laboratory X-ray diffraction (LXRD) and synchrotron X-ray diffraction (SXRD) investigations approve the single-phase face centered crystalline structure. The obtained space group is Fd3m. The average crystallite size has been determined by Debye Scherrer’s method and the Williamson Hall [W-H] method. The obtained size is found to be ~ 27 and 17 nm respectively, for both methods when the data is measured by SXRD. The scanning electron micrograph (SEM) shows the agglomeration of particles, which is confirmed by surface topography. Room temperature polarization study exposes the weaker strength of ferroelectricity, which is principally due to charge reversal in the CoCr2O4 compound. The experimental value for retaining polarization is found to be ~ 65% at room temperature (300K).

Tuning the Multiferroic Properties of BiFeO_{3} under Uniaxial Strain.

More than twenty years ago, multiferroic compounds combining in particular magnetism and ferroelectricity were rediscovered. Since then, BiFeO_{3} has emerged as the most outstanding multiferroic by combining at room temperature almost all the fundamental or applicative properties that may be desired: electroactive spin wave excitations called electromagnons, conductive domain walls, or a low band gap of interest for magnonic devices. All these properties have so far only been discontinuously strain engineered in thin films according to the lattice parameter imposed by the substrate. Here we explore the ferroelectricity and the dynamic magnetic response of BiFeO_{3} bulk under continuously tunable uniaxial strain. Using elasto-Raman spectroscopy, we show that the ferroelectric soft mode is strongly enhanced under tensile strain and driven by the volume preserving deformation at low strain. The magnonic response is entirely modified with low energy magnon modes being suppressed for tensile strain above pointing out a transition from a cycloid to an homogeneous magnetic state. Effective Hamiltonian calculations show that the ferroelectric and the antiferrodistortive modes compete in the tensile regime. In addition, the homogeneous antiferromagnetic state becomes more stable compared to the cycloidal state above a +2% tensile strain close to the experimental value. Finally, we reveal the ferroelectric and magnetic orders of BiFeO_{3} under uniaxial strain and how the tensile strain allows us to unlock and to modify in a differentiated way the polarization and the magnetic structure.

Linear magnetoelectric coupling and type-II multiferroic order in NiMn2O4

We report an unexplored type-II multiferroic order in NiMn2O4, exhibiting strong linear magnetoelectric coupling above liquid-nitrogen (LN) temperature. The compound becomes ferroelectric at ∼100 K, coinciding with ferrimagnetic ordering, with a polarization value of ∼535 μC/m2 for a poling field of 5 kV/cm. At LN temperature, the polarization value increases linearly (∼21%) with a magnetic field up to 30 kOe. Rietveld refinement of neutron diffraction patterns reveals a ferrimagnetic model with antiparallel moments at tetrahedral and octahedral sites, as well as a canting of octahedral moment persisting up to ∼100 K. Low-temperature synchrotron diffraction confirms a step-like oxygen displacement during multiferroic ordering, suggesting that the Dzyaloshinskii–Moriya interaction polarizes the intervening oxygen atoms through magnetostriction, providing a microscopic mechanism for spontaneous electric polarization in this linear magnetoelectric multiferroic compound.

Recent Progress of Multiferroicity and Magnetoelectric Effects in ABX3‐Type Perovskite Metal–Organic Frameworks

AbstractMultiferroics have been investigated extensively in the last decades due to their wide range of applications in high‐density multistate storage, spintronics, and novel multifunctional magnetic–electric devices. One peculiar subgroup of multiferroic materials comprises 3D perovskite metal–organic frameworks (MOFs) with the general formula ABX3 (A = monovalent organic cation (such as an alkali metal or protonated amine), B = divalent metal cation, X = organic anion), for their coexistence of multiple orders (electric, magnetic, and elastic, et al.). The purpose of this review is to give a representative overview of the recent progress in the field of ABX3‐type multiferroic MOFs, containing 3d magnetic metal ions at B‐site. First, the perovskite multiferroic MOFs in which X‐site is occupied by formate, is examined and summarized. In particular, magnetoelectric coupling effects, such as electric‐field tuning of magnetic properties and magnetic field control of electric polarization, and pressure control of structural/magnetic/electric properties, are described and discussed. Then, it is focused on the structural phase transitions and ferroic orders by analyzing several representative multiferroic MOFs compounds with none‐formate. To motivate the researchers in this area, some promising topics that have not yet been fully explored in perovskite multiferroic MOFs are finally proposed.

Application of on-site hybrid exchange and correlation functional in the study of multiferroic R3c BiFeO3 compound

In this work, we report calculations of the structural, electronic, magnetic, optical and ferroelectric properties of multiferroic R3c BiFeO3 compound using an on-site PBE0 hybrid and the generalized gradient approximation (GGA) exchange and correlation (XC) functional within the framework of spin density functional theory (SDFT). R3c BiFeO3 is a prototypical example of a strongly correlated and magnetoelectric material, which poses a challenge for a standard XC functional (such as GGA). We compare our results with available experimental data and those calculated using the GGA, as well as with previous SDFT calculations employing a different XC functional. We verify that PBE0 calculations of R3c BiFeO3 can predict the lattice parameters, Fe-O distances, energy band gap, spin magnetic moment of the Fe atom, magnetic order, and optical spectra, with results that are in good agreement with the experimental data. This study offers perspectives for further investigations of other multiferroic compounds and other crystalline phases of BiFeO3 using the on-site PBE0 hybrid XC functional.

Magnetic and Magnetoelectric Properties of AurivilliusThree- and Four-Layered Intergrowth Ceramics

In this work, we have prepared intergrowth of multiferroic compounds namely Bi4RTi3Fe0.7Co0.3O15-Bi3RTi2Fe0.7Co0.3O12−δ (BRTFCO15-BRTFCO12) (rare earth (R) = Dy, Sm, La) by solid-state reaction method. From the X-ray diffraction Rietveld refinement, the structure of the intergrowths was found to be orthorhombic in which satisfactory fittings establish the existence of three-layered (space group: b 2 c b) and four-layered compounds (space group: A21am). Analysis of magnetic measurements confirmed a larger magnetization for theSm-modified intergrowth compound (BSTFCO15-BSTFCO12) compared to Dy- and La-doped ones. The emergence of higher magnetic properties can be due to distortion in the unit cell when some Bi3+ ions are replaced with the Sm3+, bonding of Fe3+-O-Co3+ as well as a possible mixture of FexCoy-type nanoparticles that are formed generally in the synthesis of intergrowths. The changes in the magnetic state of the Aurivillius intergrowths have been reflected in the magnetoelectric (ME) coupling: higher ME coefficient (~30 mV/Cm-Oe) at lower magnetic fields and is constant up to 3 kOe. The results were corroborated by Raman spectroscopy and variation of temperature with magnetization data. The results revealed that the RE-modified intergrowth route is an effective preparative method for higher-layer Aurivillius multiferroic ceramics.

Photoferroic prospective of multiferroic HoMnO3 compound, evaluated on the base of the DFT study of its magnetic, electronic, and optical properties

In this work, non-collinear spin density functional theory based all-electron full-potential linearized augmented plane wave electronic structure method have been employed to study magnetic, electronic, and optical properties of multiferroic HoMnO3 compound in order to evaluate its potential to be used in photovoltaic applications. Exchange and correlation effects of the Ho 4f- and Mn 3d-electrons were treated on the base of the local spin density approximation including effective Hubbard (Ueff) correction. We concluded that the ground state magnetic structure should be described by Γ3 irreducible representation of the P63cm space group, for both the Mn and the Ho magnetic sub-lattices. The calculated indirect and direct band gaps, corresponding to the transition from the O 2p-to the Mn 3d-states, are found to be 1.25 eV and 1.4 eV, respectively, in very good agreement with the experimental findings. Calculated dielectric tensor spectra are found to be in satisfactory agreement with the experiment as well. On the base of these results, we investigated photoferroic properties of the HoMnO3 by calculating its absorption coefficient spectrum and the effective mass tensor of the photogenerated electrons and holes. By comparing results with those of isostructural LuMnO3 and the YMnO3 multiferroics, we concluded that the HoMnO3 exhibits similar photoferroic properties, a fact that classifies it as a material suitable for photovoltaic applications.

γ-BaFe2O4: a fresh playground for room temperature multiferroicity

Multiferroics, showing the coexistence of two or more ferroic orderings at room temperature, could harness a revolution in multifunctional devices. However, most of the multiferroic compounds known to date are not magnetically and electrically ordered at ambient conditions, so the discovery of new materials is pivotal to allow the development of the field. In this work, we show that BaFe2O4 is a previously unrecognized room temperature multiferroic. X-ray and neutron diffraction allowed to reveal the polar crystal structure of the compound as well as its antiferromagnetic behavior, confirmed by bulk magnetometry characterizations. Piezo force microscopy and electrical measurements show the polarization to be switchable by the application of an external field, while symmetry analysis and calculations based on density functional theory reveal the improper nature of the ferroelectric component. Considering the present findings, we propose BaFe2O4 as a Bi- and Pb-free model for the search of new advanced multiferroic materials.

Structural, complex dielectric, Ac conductivity and impedance properties of Mn3-xCrxTeO6 (x = 0.02, 0.04, 0.06 and 0.08) compounds

In this communication, the synthesis of polycrystalline Mn3-xCrxTeO6 (MCTO) (x = 0.02, 0.04, 0.06 and 0.08) compounds is carried out using the standard high-temperature solid-state reaction (SSR) method. The X-ray Diffraction (XRD) technique revealed the trigonal (hexagonal axes) crystal structure of MCTO compounds. The doping of Chromium (Cr) on the Mn site does not affect the structure of the compound. The compositional purity and morphological observations are also investigated. Dielectric parameters are examined throughout a wide frequency range. Detailed investigation obtained by theoretical fitting of the cole-cole model revealing a non-Debye type relaxation mechanism which is also evident from the complex modulus studies. An investigation on electrical conductivity is carried out by conceptually fitting experimental data using a power law and indicates a Correlated Barrier Hopping mechanism in MCTO compounds as the cause of conduction. The resistance and capacitance were validated by impedance analysis, and the effect of grains and grain boundaries was also studied accordingly. In-depth, this study demonstrates an effective synthesis approach and a thorough examination of Cr-doped Mn3TeO6 multiferroic compounds, potentially providing fundamental attributes to investigate their applications in various fields of multiferroics.

Emergence of collinear magnetic structure in Tb-doped BiFeO3

The search for ways to realize the multiferroic potential of BiFeO3-based compounds is being relevant for three decades. The major problem is a magnetic spatial spin-modulated structure (SSMS) that nullifies the net magnetic moment over the sample volume. In this paper, we research the effect of bismuth ferrite doping with magnetic Tb3+ ions.With the help of zero-field nuclear magnetic resonance (ZF NMR) spectroscopy, we reveal a change in the type of anisotropy from “easy-axis” to “easy-plane” even at 1.5 % terbium doping. Moreover, at 8.5 % Tb doping, the magnetic structure becomes collinear, SSMS deteriorates, while the crystal structure remains rhombohedral. We also observe an additional high-frequency line, similar to the lines found in the La- and Sr-doped BFO spectra, at a frequency of 75.85 MHz. Such a combination of characteristics gives this composition every chance of being a promising multiferroic compound.

Effects of tensile strain on the electronic, optical and ferroelectric properties of a multifunctional R3c InFeO3 compound

The search for materials with appropriate ferroelectric and photovoltaic properties is an intense field of research. The main objective of these studies is to obtain efficient materials for solar cell applications. In this work, non-collinear spin density functional theory calculations are performed to describe the electronic, optical, and ferroelectric properties of a multiferroic R3c InFeO3 compound under tensile strain. Our studies reveal that under conditions of tensile strain, this material had ideal fundamental properties for photovoltaic applications. Under 9% tensile strain of the R3c InFeO3 unit cell volume (a = 5.536 Å and c = 13.808 Å), a direct energy band gap of 1.74 eV was found. With this energy band gap, the material absorbs the entire range of visible light, and for a film thickness of up to 100 nm it reaches a maximum photoconversion efficiency of 20%, a higher value than observed in some semiconductors that are used in practice. Furthermore, the effective mass of charge carriers (m*), and the exciton binding energy (Eb) are significantly decreased (m* < 0.4 m0 and Eb < 1.0 meV), which likely to lead to better charge mobility and easier separation of the electron-hole pair in the process of photoabsorption. Under this level of strain, the spontaneous electric polarization was reduced to 77.6 µC/cm2, a value that is still higher than other ferroelectric-photovoltaic materials.

Unveiling unconventional ferroelectric switching in multiferroic Ga0.6 Fe1.4O3 thin films through multiscale electron microscopy investigations

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 Ga0.6Fe1.4O3 multiferroic compound. A wide scale precession-assisted electron diffraction tomography study first allows the determination of the structure the compound adopts in thin films, and even permits the refinement of the atomic positions within this structure. Cationic mobility is suggested for two of the atomic positions through the existence of extra electronic density. A local in situ high resolution scanning transmission electron microscopy study then allows confirming these mobilities by directly spotting the cationic displacements on successively acquired images. The whole study confirms an unconventional switching mechanism via local domain wall motion in this compound.