Ferromagnetic Moment Research Articles

Study of Physical Properties of Co Substituted GdFeO3 Orthoferrites and Evaluation of Their Antibacterial Activity

Perovskite-type GdFe1‒xCoxO3 (0.00 ≤ × ≤ 0.25) solid solution is prepared with the citrate auto combustion technique. The electrical properties and the Seebeck coefficient are measured in the temperature range 300–600 K to elucidate the Co doping effect on the physical properties of the GdFeO3. The variation of the magnetic susceptibility (χ) with the absolute temperature as a function of different magnetic fields is investigated. The data reveals that the samples under investigation are G-type antiferromagnetic with a weak ferromagnetic moment results due to a slight canting. The decrease of the molar magnetic susceptibility χ with the temperature ensures the presence of a weak ferromagnetic behavior originated from the Dzyaloshinskii–Moriya interaction. The ac conductivity (σac) is increased by increasing the frequency and follows Jonscher’s power law. For the investigated samples, the non-overlapping small polarons are responsible for the conduction in the low- temperature region. While at high temperatures, the correlated barrier hopping (CBH) mechanism takes place. The Seebeck coefficient changes from a negative to a positive value with increasing Co2+ ion concentration and increases with rising temperature up to 550 K. The total variation of the Seebeck coefficient signifies the p-type conduction (holes) as charge carriers along with the designated temperature range. The antibacterial activity of the investigated samples is studied. Finally, the obtained data demonstrates the crucial role of doping in improving the multiferroic properties, which would open up the possibility of using GdFe1‒xCoxO3 in fabricating magnetic field sensors and data storage devices.

Structural and magnetic properties of the interstitial carbide-hydride NdScSiC0.5H0.2

We report the synthesis of the first carbide-hydride phase obtained in the family of equiatomic intermetallics RTX (R = rare earth, T = transition metal, X = p-block element) by insertion of light elements. We prepared the NdScSiC0.5H0.2 compound by solid-gas reaction, by exposing the carbide NdScSiC0.5 to 40 bars of H2 gas at 450 °C. It crystallizes in the La2Fe2Se2O3-type structure with H and C atoms occupying Nd4 tetrahedral and Nd2Sc4 octahedral interstices, respectively. The H site is only partly filled owing to the presence of Nd–C covalent bonding that prevents the formation of Nd–H bonding through antagonist effect. The carbide-hydride was characterized through magnetic measurements, specific heat and powder neutron diffraction. Remarkably, hydrogenation of the carbide provokes a quite drastic effect on the magnetic properties by changing the ground state from a ferromagnetic (TC∼70 K) to an antiferromagnetic one (TN = 10 K). The magnetic structure of NdScSiC0.5H0.2 consists of double layers of ferromagnetic Nd moments aligned along the c-axis and coupled antiferromagnetically along this axis. This magnetic structure results in a field-induced metamagnetic behaviour as pointed out by magnetisation isotherms.

Spin-Hall magnetoresistance in Ta/Cr/YIG trilayers with different Cr thicknesses

We report an investigation of spin-Hall magnetoresistance (SMR) in Ta/Cr/Y3Fe5O12 (Ta/Cr/YIG) trilayers with different thicknesses of the Cr inserted layer. The Ta/Cr/YIG film with a 1-nm-thick Cr layer shows a maximum SMR of 4.2×10-4 at 100 K, which is an order of magnitude larger than that previously reported in the Ta/YIG or Cr/YIG systems. The enhancement of SMR in the Ta/Cr/YIG is ascribed to the strong spin–orbit coupling (SOC) effect of both Ta and Cr and the anti-oxidation protection by the Ta coating. A negative SMR different from the conventional SMR is found for the Ta/Cr/YIG with the Cr thicknesses of 3 and 6 nm at the temperature below 100 and 260 K, respectively, which suggests the occurrence of the spin-flop coupling between the antiferromagnetic Cr and ferromagnetic YIG moments. Both the anisotropic magnetoresistance (AMR) and the anomalous-Hall resistance (AHR) indicate an induced ferromagnetism of Cr which is likely due to the spin-flop transition or the uncompensated magnetic moments. Our results suggest that the 3d transition metal Cr can be used as a spin current generator, and the antiferromagnetic structure of Cr can be employed to regulate the transport of spin current.

Magnetic structure of undistorted hexagonal ferrites, Lu0.2In0.8FeO3

We report on the crystal and magnetic structure of bulk hexagonal (Lu,In)FeO3. Neutron powder diffraction revealed that Lu0.2In0.8FeO3 has a single-phase P63/mmc structure down to T ≈ 3 K and shows an antiferromagnetic transition at TN ≈ 164 K. Unlike the distorted hexagonal LuFeO3 family with an A2(Γ2)-type spin configuration, undistorted hexagonal Lu0.2In0.8FeO3 shows either an A1(Γ1) or a B1(Γ3)-type spin configuration below TN, which does not produce the c-directional canted ferromagnetic moment. A significant reduction in the ordered magnetic moment was observed at 3 K without trimerization, and hints of a magnetic cluster state were observed in the paramagnetic phase near room temperature. Therefore, the system presents a rare example to study the geometrically frustrated magnetism in the undistorted hexagonal magnet that has a perfect triangular lattice below room temperature.

Evidence for ferromagnetic order in the CoSb layer ofLaCoSb2

The emergence of unconventional superconductivity is generally considered to be related to spin fluctuations. Unveiling the intriguing behaviors of spin fluctuations in parent compounds with layered transition-metal ions may shed light on the search for exotic unconventional superconductors. Here, based on the framework of the first-principles calculations, we theoretically propose that LaCoSb$_2$ is a weak antiferromagnetic layered metal with an in-plane ferromagnetic moment of 0.88 $\mu_B$ at the Co sites, as a candidate parent compound of the cobalt-based superconductors. Importantly, this theoretical finding is experimentally supported by our magnetization measurements on polycrystalline samples of LaCo$_{0.78}$Sb$_2$. Following the symmetry analysis, we suggest a possible $p$-wave superconductivity hosted in doped LaCoSb$_2$ emerging at the verge of ferromagnetic spin fluctuations, which implies potential applications in topological quantum computing in future.

Studies on multifunctional properties of GdFe1−xCoxO3 multiferroics

Multiferroics—materials attract considerable attention, due to their fascinating physics properties. The motivating physical properties of GdFe1−xCoxO3 (0.00 ≤ x ≤ 0.25) orthorhombic structure were adjusted in a controlled way by modifying the composition through the synthesis processes. The orthorhombic structure within the space group Pbnm is confirmed through X-ray diffraction patterns. The data reveal that the samples under investigation are G-type antiferromagnetic with a weak ferromagnetic moment. Dzyaloshinskii–Moriya interaction is a crucial source of the observed weak ferromagnetic behavior for the investigated samples. An anisotropy constant for GdFe0.9Co0.1O3 is approximately equal to 4065 emu Oe/gm, which is 9 times greater than that of GdFeO3 samples. The higher values of anisotropic constant K indicate that the prepared samples will be promising and helpful for technological applications at a variety of temperatures. Cobalt doping has a unique advantage as it reduces the switching field distribution and the change of the entropy (ΔS) of the investigated samples. The presence of Gd3+–O2− 2p, Fe3+–O2− 2p and Co–O-2p hybridization stabilizes the ferroelectric distortion causing an improvement in ferroelectric property. The effects of pH value and the contact time on the adsorption progression were studied and optimized to obtain the maximum possible adsorption efficiency of the Gadolinium/cobalt samples. The use of GdFe0.8Co0.2O3 removes 98% of lead from the waste water. The specific advantages of the investigated samples are ease of separation, high adsorption per unit area, low cost as well as recycled with significant efficiency. The investigated samples are recommended to be used as a reusable adsorbent for the highly efficient removal of lead metal ions from aqueous solutions.

Ag8+ ion irradiation modulated structural, microstructural, defect, and magnetization in ZnO thin films

The irradiation effect of high energy silver ion (Ag8+) has been investigated on ZnO thin films to understand their impact on structural, microstructural, optical, electronic and magnetic properties. The RF sputtered pristine ZnO/Si thin films are polycrystalline and highly textured along (0 0 2) plane. The irradiated ZnO/Si samples showed enhanced structural and microstructural defects with irradiation time. The lattice parameters have reduced for irradiated ZnO thin films, suggesting structural deformation. The irradiation has resulted into enhanced defect density and strain in these thin films. A weak room temperature ferromagnetic moment (3.24 × 10−4 emu cm−2) has been observed, which has reduced drastically for Ag8+ irradiated samples up to 1.05 × 10−4 emu cm−2. The observed reduction in saturation magnetization has been attributed to the enhanced microstructural defects, lowering the free charge carriers and increasing the recombination centers simultaneously.

Long-range and local crystal structures of the Sr1−xCaxRuO3 perovskites

The crystal structures of the Sr1-xCaxRuO3 perovskites are investigated using both long range and local structural probes. High resolution synchrotron powder X-ray diffraction characterization at ambient temperature shows that the materials are orthorhombic to high precision, and we support previous work showing that Ca2+ substitution for Sr2+ primarily changes the tilting of rigid corner-sharing RuO6 octahedra at their shared oxygen vertices. X-ray pair distribution function analysis for SrRuO3, CaRuO3 and one intermediate composition show them to be locally monoclinic, and no long range or local phase transitions are observed between 80 and 300 K for materials with intermediate compositions. High-resolution transmission electron microscopy shows that the Sr/Ca distribution is random at the nanoscale. We plot magnetic characteristics such as the ferromagnetic Tc, Curie-Weiss theta, effective moment, and ambient temperature susceptibility vs. the octahedral tilt and unit cell volume.

Origin of negative magnetization phenomena in (Tm1−xMnx)MnO3 : A neutron diffraction study

$(\mathrm{T}{\mathrm{m}}_{1\ensuremath{-}x}\mathrm{M}{\mathrm{n}}_{x})\mathrm{Mn}{\mathrm{O}}_{3}$ solid solutions were synthesized at a high pressure of 6 GPa and a high temperature of about 1570--1670 K for 2 h for $x=0$, 0.1, 0.2, and 0.3. Magnetic, dielectric, and neutron diffraction measurements revealed that the introduction of magnetic ${\mathrm{Mn}}^{2+}$ cations into the A site leads to an incommensurate spin structure for $x=0.1$ and to a ferrimagnetic structure for $x\ensuremath{\ge}0.2$. Commensurate magnetic structures have a much larger correlation length $(\ensuremath{\sim}400\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$ for $x=0,\ensuremath{\sim}600\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$ for $x=0.3)$ than the incommensurate magnetic structure $(\ensuremath{\sim}12\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$ for $x=0.1)$. The presence of ${\mathrm{Tm}}^{3+}$ and ${\mathrm{Mn}}^{2+}$ (with different sizes) at the A site causes significant microstrain effects along the $a$ direction which are absent for $x=0$ and get stronger with increasing $x$. Magnetic ordering occurs at the N\'eel temperature ${T}_{N}=37\phantom{\rule{0.28em}{0ex}}\mathrm{K}\phantom{\rule{4pt}{0ex}}(x=0.1)$ and at the ferrimagnetic Curie temperatures ${T}_{C}=75\phantom{\rule{0.28em}{0ex}}\mathrm{K}\phantom{\rule{4pt}{0ex}}(x=0.2)$ and ${T}_{C}=104\phantom{\rule{0.28em}{0ex}}\mathrm{K}\phantom{\rule{4pt}{0ex}}(x=0.3)$. Ordering of magnetic Mn moments triggers short-range order (for $x=0.1)$ and long-range order (for $x\ensuremath{\ge}0.2)$ of the ${\mathrm{Tm}}^{3+}$ cations at the same temperature---an unusual situation in perovskite materials with a simple ${\mathrm{GdFeO}}_{3}$-type $Pnma$ structure. For $x=0.1$, long-range IC magnetic order [with propagation vector $\mathbf{k}=({k}_{0},0,0)$ and ${k}_{0}\ensuremath{\approx}0.40]$ of ${\mathrm{Mn}}^{3+}$ and ${\mathrm{Mn}}^{4+}$ cations at the B site coexists with short-range order of ${\mathrm{Tm}}^{3+}$ and ${\mathrm{Mn}}^{2+}$ moments at the A site. Short-range order is induced at the N\'eel temperature ${T}_{N}=37\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, increases towards an additional specific heat anomaly at $T=4\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, and remains at lower temperature. The ferrimagnetic structure [with propagation vector $\mathbf{k}=(0,\phantom{\rule{0.28em}{0ex}}0,\phantom{\rule{0.28em}{0ex}}0)]$ consists of ferromagnetically ordered ${\mathrm{Mn}}^{3+}$ and ${\mathrm{Mn}}^{4+}$ cations at the B site which are coupled antiferromagnetically with ordered ${\mathrm{Mn}}^{2+}$ moments at the A site. ${\mathrm{Tm}}^{3+}$ moments adopt a zigzag magnetic structure which contains a macroscopic ferromagnetic moment that aligns with the direction of the ordered ${\mathrm{Mn}}^{2+}$ moments. Towards low temperature, the ordered ${\mathrm{Tm}}^{3+}$ moments strongly increase and overcome the saturated magnetic Mn moments at the B site, and this behavior results in the observation of magnetization reversal or negative magnetization phenomena with a compensation temperature of about 15 K at small magnetic fields in the $x=0.2$ and 0.3 samples. This is a classical mechanism of the magnetization reversal effects for ferrimagnets.

Critical behavior of perpendicular exchange bias in Ru/Pd/Co/Pt/Cr2O3/Pd stacked films

The proximity effect in a heavy metal attached to a ferromagnetic (FM) layer results in varied interface magnetism. In this study, we investigated the critical behavior of the perpendicular exchange bias in a Ru/Pd/Co/Pt/Cr2O3/Pd stacked film, with focus on the influence of the Pt spacer layer. The apparent critical exponent β increases with increasing Pt thickness. We discussed the possible mechanism from the perspective of the induced magnetic moment of Pt and interfacial exchange coupling. The former was explored based on X-ray magnetic circular dichroism, which revealed that the magnetic moment of Pt was almost temperature-independent within the studied temperature regime. This suggests that the interfacial FM moment is stable. The latter, i.e., the reduction of the interfacial exchange coupling by the Pt spacer layer, is a possible cause of the increase in β, as theoretically predicted.

Quantification of local Ising magnetism in rare-earth pyrogermanates Er2Ge2O7 and Yb2Ge2O7

Recently, a local-Ising-type magnetic order was inferred from neutron diffraction of the antiferromagnetic ${\mathrm{Er}}_{2}{\mathrm{Ge}}_{2}{\mathrm{O}}_{7}$ (pg-ErGO) with an applied magnetic field. Here, we use neutron spectroscopy to investigate the energetics of pg-ErGO and the isostructural ${\mathrm{Yb}}_{2}{\mathrm{Ge}}_{2}{\mathrm{O}}_{7}$ (pg-YbGO) to evaluate the adequacy of the local-Ising description. To begin, we generate a model of the magnetic structure of pg-YbGO using neutron diffraction and find a net ferromagnetic moment. While pg-ErGO and pg-YbGO have highly symmetric crystal structures ($P{4}_{1}{2}_{1}2$ tetragonal space group 92) with only one trivalent rare-earth magnetic site, the point symmetry of the rare-earth site is low with only a single symmetry element (point group ${\mathrm{C}}_{1}$). For both compounds, the energy scale of the first excited state is large compared to the magnetic ordering temperature, suggesting Ising character. The ground-state Kramer's doublet of both compounds is dominated by the maximal ${m}_{\mathrm{J}}$ component. However, the low point group symmetry of the rare-earth site leads to finite mixing of all other ${m}_{\mathrm{J}}$'s, which suggests potential deviations from Ising behavior. Moreover, quasielastic scattering is observed deep in the ordered state of pg-ErGO and pg-YbGO that may be due to non-Ising behavior. The dominant magnetic interaction in both compounds is found to be magnetostatic by considering the magnetic excitations in the ordered state. From consideration of these data, the pg-YbGO is more Ising-like than pg-ErGO. Also, quantum multicritical points are anticipated with applied magnetic field in both compounds.

Controllable Ferromagnetism in Super-tetragonal PbTiO3 through Strain Engineering.

The coupling strain in nanoscale systems can achieve control of the physical properties in functional materials, such as ferromagnets, ferroelectrics, and superconductors. Here, we directly demonstrate the atomic-scale structure of super-tetragonal PbTiO3 nanocomposite epitaxial thin films, including the extraordinary coupling of strain transition and the existence of the oxygen vacancies. Large strain gradients, both longitudinal and transverse (∼3 × 107 m-1), have been observed. The original non-magnetic ferroelectric composites notably evoke ferromagnetic properties, derived from the combination of Ti3+ and oxygen vacancies. The saturation ferromagnetic moment can be controlled by the strain of both the interphase and substrate, optimized to a high value of ∼55 emu/cc in 10-nm thick nanocomposite epitaxial thin films on the LaAlO3 substrate. Strain engineering provides a route to explore multiferroic systems in conventional non-magnetic ferroelectric oxides and to create functional data storage devices from both ferroelectrics and ferromagnetics.

Frustrated magnetism in the J1−J2 honeycomb lattice compounds MgMnO3 and ZnMnO3 synthesized via a metathesis reaction

We investigated the magnetic properties of the ilmenite-type manganates $\mathrm{MgMn}{\mathrm{O}}_{3}$ and $\mathrm{ZnMn}{\mathrm{O}}_{3}$, both of which are composed of a honeycomb lattice of magnetic $\mathrm{M}{\mathrm{n}}^{4+}$ ions. Both compounds show antiferromagnetic order with weak ferromagnetic moments. In particular, $\mathrm{MgMn}{\mathrm{O}}_{3}$ exhibits a magnetization ``reversal'' behavior which can be described by the $N$-type ferrimagnetism in the N\'eel's classification. The relationship between the magnetic properties and the crystal and magnetic structures probed by the neutron diffraction experiments indicates that the two honeycomb lattice magnets have different ${J}_{1}\ensuremath{-}{J}_{2}$ parameter sets, placing them in the distinct regions in the phase diagram; both nearest neighbor (NN) and next nearest neighbor (NNN) exchange interactions are antiferromagnetic in $\mathrm{MgMn}{\mathrm{O}}_{3}$, while NN and NNN interactions become ferromagnetic and antiferromagnet, respectively, in $\mathrm{ZnMn}{\mathrm{O}}_{3}$.

Nonvolatile Electric Control of the Anomalous Hall Effect in an Ultrathin Magnetic Metal

AbstractLow‐dimensional magnetism has been boosted by the recent discovery of the ferromagnetism in layered two‐dimensional (2D) semiconductors. Although the macroscopic magnetic moments of 2D ferromagnets are weak, the anomalous Hall effect (AHE) can serve as a versatile electric probe to their magnetic properties. Here, the nonvolatile electric‐field manipulation of the AHE in an ultrathin metallic ferromagnet with perpendicular magnetic anisotropy at room temperature is reported, which is achieved by the electrostatic modulation of the longitudinal resistivity via a ferroelectric substrate without varying magnetization. Therefore, this work demonstrates an electric‐field‐controlled room‐temperature memory device based on the zero‐magnetic‐field anomalous Hall resistance of an ultrathin ferromagnet. More importantly, the experimental results disentangle magnetization and anomalous Hall resistance. As a result, the study reveals a linear decrease of anomalous Hall conductivity with normal conductivity, which is distinct from previous scaling relations. Accordingly, this work manifests a universe avenue to harnessing the AHE in low‐dimensional magnetic materials.

The effect of carrier doping on magnetism and electronic behavior in double perovskite La2ZnIrO6

Tuning of spin–orbit coupling and electron correlation effects in iridates by introducing electron or hole carriers can produce interesting physical phenomena. In this work, we experimentally investigate the electron/hole doping effect on magnetism and electrical transport in the canted antiferromagnetic (AFM) double perovskite La2ZnIrO6, where hole/electron doping are realized in two serial La2Zn1−xLixIrO6 (0 ⩽ x ⩽ 0.35) and La2Zn1−y Gay IrO6 (0 ⩽ y ⩽ 0.3) compounds, respectively. The x-ray photoelectron spectroscopy (XPS) reveals the existence of Ir5+ and Ir3+ oxide states in the Li+ and Ga3+ doped La2ZnIrO6. The magnetic susceptibilities and electron spin resonance (ESR) results reveal different responses between the Ir5+(5d4) and Ir3+ (5d6) ions in doped La2ZnIrO6, the Ir5+ ions have Van-Vleck paramagnetic contribution contrast to the completely nonmagnetic Ir3+ ions. Moreover, the Li+ doping cause more dramatic suppression of transition temperature (TN) and net ferromagnetic (FM) moments. All the Li+/Ga3+ doped samples remain Mott insulating state well fitted by the variable-range-hopping (VRH) transport mechanism. As a comparison, hole-doping is more effective to enhance the electrical conductivity than the case of electron, suggesting possible asymmetry of density of states nearby the Fermi level.

Ferromagnetic excess moments and apparent exchange bias in FeF2 single crystals

The anisotropic antiferromagnet FeF2 has been extensively used as an antiferromagnetic layer to induce exchange bias effects in ferromagnetic/antiferromagnetic bilayers and heterostructures. In this work, an apparent exchange bias occurring in the low temperature hysteresis loops of FeF2 single crystals is investigated. A detailed investigation of the hysteresis and remnant magnetization indicates that the observation of an apparent exchange bias in FeF2 stems from an intrinsic excess moment associated with a distortion of the antiferromagnetic structure of piezomagnetic origin.

Wurtzite CuNi2InS4 Nanocrystals: A Quaternary Chalcogenide Magnetic Semiconductor.

For the first time, quaternary chalcogenide CuNi2InS4 nanocrystals with a wurtzite structure have been designed and fabricated as a new magnetic semiconductor. The phase structure analysis suggests that the synthesized wurtzite CuNi2InS4 phase has a disordered structure in which Cu+, Ni2+, and In3+ ions share the same lattice site of the unit cell with a random cation distribution. The prepared CuNi2InS4 nanocrystals have uniform bullet-like morphology, small size distribution, good monodispersity, and high crystallinity. The magnetic properties investigation reveals that the wurtzite CuNi2InS4 nanocrystals can exhibit a weak ferromagnetic moment with the blocking temperature at around 13 K thanks to the disordered wurtzite structure and the high content of magnetic Ni2+ ions. As for the semiconducting properties, the as-obtained wurtzite CuNi2InS4 nanocrystals show a strong and broad visible light absorption and have a direct bandgap of 1.45 eV. Due to their favorable optical properties, the fabricated thin film of CuNi2InS4 nanocrystals exhibits a good photoelectric response to the solar spectrum, which makes the obtained new phase potential candidate for applications in the photovoltaics. This work demonstrates a new metastable I-II2-III-VI4 chalcogenide that can be used to render multiple functionalities and applications.

Electronic structure, magnetism and elastic properties of Inverse Perovskite Carbide: A first principles study

Antiperovskite materials display many fascinating properties like that of perovskites. We summed up the electronic, magnetic and mechanical properties of Ni3LiC compound in this work, via density functional theory calculations. The structural optimization via the Birch-Murnaghan approach supply the lattice parameters and ground state energy within the Fm-3m space group. Spin resolved band occupation and density of states define its metallic nature with a total ferromagnetic moment of 0.76 μB. The effect of uniform strain is analysed, which shows the increase in magnetic moment with the expansion of the lattice and vice versa. The speculated elastic constants and their different combinations conclude the mechanical strength and stability of this material. The large bulk modulus and B/G ratio claims its ductile and incompressible nature and the Zener's parameter reflects the exhibition of anisotropic properties.

De Haas-van Alphen effect of correlated Dirac states in kagome metal Fe3Sn2

Primarily considered a medium of geometric frustration, there has been a growing recognition of the kagome network as a harbor of lattice-borne topological electronic phases. In this study we report the observation of magnetoquantum de Haas-van Alphen oscillations of the ferromagnetic kagome lattice metal Fe3Sn2. We observe a pair of quasi-two-dimensional Fermi surfaces arising from bulk massive Dirac states and show that these band areas and effective masses are systematically modulated by the rotation of the ferromagnetic moment. Combined with measurements of Berry curvature induced Hall conductivity, our observations suggest that the ferromagnetic Dirac fermions in Fe3Sn2 are subject to intrinsic spin-orbit coupling in the d electron sector which is likely of Kane-Mele type. Our results provide insights for spintronic manipulation of magnetic topological electronic states and pathways to realizing further highly correlated topological materials from the lattice perspective.

Direct coupling of ferromagnetic moment and ferroelectric polarization in BiFeO3

The spin-driven component of electric polarization in a single crystal of multiferroic BiFeO$_{3}$ was experimentally investigated in pulsed high magnetic fields up to 41 T. Sequential measurements of electric polarization for various magnetic field directions provide clear evidence of electric polarization normal to the hexagonal $c$ axis (${\bf P}_{\rm t}$) in not only the cycloidal phase, but also the field-induced canted antiferromagnetic phase. The direction of ${\bf P}_{\rm t}$ is directly coupled with the ferromagnetic moment in the canted antiferromagnetic phase, and thus controlled by changing the direction of the applied magnetic field. This magnetoelectric coupling is reasonably reproduced by the metal-ligand hybridization model.