Magnetic ordering induced ferroelectricity in α-Cu 2 V 2 O 7 studied through non-magnetic Zn doping
TL;DR: In this paper, the magnetic and electronic properties of Cu2-xZnxV2O7 were studied by magnetization, specific heat, and dielectric measurements, and it was shown that magneto-electric coupling is nonlinear in nature, which is in agreement with the Landau theory of continuous phase transition.
Abstract: We have studied the magnetic and electronic properties of Cu2-xZnxV2O7 by magnetization, specific heat, and dielectric measurements. X-ray structural analysis shows a Zn-mediated phase transition from the α- to the β-phase beyond a critical Zn concentration of xc = 0.15. While Cu2V2O7 exhibits a canted antiferromagnetism with an associated weak ferromagnetism in the α-phase, the β-phase is purely antiferromagnetic. The spin canting arises due to the Dzyaloshinskii-Moriya exchange interaction in the anti-symmetric α-phase. The temperature dependence of the heat capacity for the sample in the α-phase shows a clear lambda like transition at a temperature where the magnetic susceptibility also displays an anomaly and indicates an onset of long range magnetic ordering. Dielectric properties display a clear anomaly around the magnetic transition temperature in α-Cu2V2O7. The anomaly weakens with the increase in the Zn concentration and disappears at the doping level where α to β phase transition occurs. This confirms the existence of magneto-electric coupling in α-Cu2V2O7 but not in its β-phase. Analysis of the experimental data shows that magneto-electric coupling is non-linear in nature, which is in agreement with the Landau theory of continuous phase transition. So, α-Cu2V2O7 establishes itself as a promising candidate for magnetic multiferroics.
Citations
More filters
TL;DR: In this paper, the authors experimentally observed the spin Seebeck effect (SSE) in the polar antiferromagnet and found that the magnon scattering plays an important role in the SSE.
Abstract: Spin currents in antiferromagnetic materials have recently attracted much interest in the field of spintronics. Although the thermal generation effect of spin currents, as in the spin Seebeck effect (SSE), is powerful for their study, the SSE in antiferromagnets has been experimentally studied only for Cr${}_{2}$O${}_{3}$ and MnF${}_{2}$. In this work, the authors experimentally observe the SSE in the polar antiferromagnet \ensuremath{\alpha}-Cu${}_{2}$V${}_{2}$O${}_{7}$. Comparison of the experimental results with calculations using magnetic parameters determined by neutron scattering studies reveals that the magnon scattering plays an important role in the antiferromagnetic SSE observed in \ensuremath{\alpha}-Cu${}_{2}$V${}_{2}$O${}_{7}$.
24 citations
TL;DR: In this paper , a series of 10% Co(ii)-doped CuV (Co10%-CuV) samples were developed with varying cobalt(ii) doping concentrations deploying a relatively simple solid state synthetic procedure.
Abstract: Strategically doped metal oxide nanomaterials signify a rapidly growing genre of functional materials with a wide range of practical applications. Copper vanadate (CuV) represents one such highly active system, which has been rarely explored following its doping with an abundant first-row transition metal. Here, we have developed a series of CuV samples with varying cobalt(ii) doping concentrations deploying a relatively simple solid state synthetic procedure. Among the samples, the 10% Co(ii)-doped CuV (Co10%–CuV) exhibited excellent reactivity for both the H2 evolution reaction (HER) and glycerol oxidation reaction (GOR) in an alkaline aqueous medium (pH 14.0) during cathodic and anodic scans, respectively. During this dual-active catalysis, surface-immobilized Co10%–CuV operates at exceptionally low overpotentials of 176 mV and 160 mV for the HER and GOR, respectively, while achieving 10 mA cm2 current density. The detailed spectroscopic analysis revealed the formation of formate as the major product during the GOR with a faradaic efficiency of >90%. Therefore, this Co10%–CuV can be included on either side of a two-electrode electrolyzer assembly to trigger a complete biomass-driven H2 production, establishing an ideal carbon-neutral energy harvest process.
4 citations
TL;DR: In this article , the authors report the single-crystal growth of Mn 2 V 2 O 7 and the results of magnetic susceptibility, high-field magnetization up to 55 T and high-frequency electric spin resonance (ESR) measurements for its low-temperature α phase.
Abstract: Abstract We report the single-crystal growth of Mn 2 V 2 O 7 and the results of magnetic susceptibility, high-field magnetization up to 55 T and high-frequency electric spin resonance (ESR) measurements for its low-temperature α phase. Two antiferromagnetic (AFM) ordering at 17.5 K and 3 K and obvious magnetic anisotropy are observed in α -Mn 2 V 2 O 7 upon cooling. In pulsed high magnetic fields, the compound reaches the saturation magnetic moment of ∼10.5 μ B for each molecular formula at around 45 T after two undergoing AFM phase transitions at H c1 ≈ 16 T, H c2 ≈ 34.5 T for H //[ 1 1 ˉ 0 001 1 1 ˉ 0 001 001
TL;DR: In this article, the effect of doping of both magnetic (Co) and nonmagnetic (Mg) ions at the Cu site on phase transition in polycrystalline α-Cu2V2O7 through structural, magnetic, and electrical measurements was studied.
Abstract: We have studied the effect of doping of both magnetic (Co) and nonmagnetic (Mg) ions at the Cu site on phase transition in polycrystalline α-Cu2V2O7through structural, magnetic, and electrical measurements. x-ray diffraction reveals that Mg doping triggers an onset of α- to β-phase structural transition in Cu2-xMgxV2O7above a critical Mg concentration xc=0.15, and both the phases coexist up to x=0.25. Cu2V2O7possesses a non-centrosymmetric(NCSM) crystal structure and antiferromagnetic (AFM) ordering along with a non-collinear spin structure in the α phase, originated from the microscopic Dzyaloshinskii-Moriya(DM) interaction between the neighboring Cu spins. Accordingly, a weak ferromagnetic behavior has been observed up to x=0.25. However, beyond this concentration, Cu2-xMgxV2O7exhibits complex magnetic properties. A clear dielectric anomaly is observed in α-Cu2-xMgxV2O7around the magnetic transition temperature, which loses its prominence with the increase in Mg doping. The analysis of experimental data shows that the magnetoelectric coupling is nonlinear, which is in agreement with the Landau theory of continuous phase transitions. Co doping, on the other hand, initiates a sharp α to β phase transition around the same critical concentration xc=0.15 in Cu2-xCoxV2O7but the ferromagnetic behavior is very weak and can be detected only up to x=0.10. We have drawn the magnetic phase diagram which indicates that the rate of suppression in transition temperature is the same for both types of doping, magnetic (Co) and nonmagnetic (Zn/Mg).
TL;DR: In this paper , the thermal evolution of the lattice parameters was determined by high temperature X-ray Diffraction revealing negative thermal expansion coefficients and the optimal conditions to obtain a dense target in order to produce thin films by the Pulsed Laser Deposition (PLD) technique.
Abstract: Polymorphic phases of copper pyrovanadate (α- and β-Cu2V2O7) were synthesized by solid state reaction and the mechanisms governing the phase transitions have been highlighted by the ThermoGravimetric Analysis (TGA) and the Differential Scanning Calorimetry (DSC). The thermal evolution of the lattice parameters was determined by high temperature X-ray Diffraction revealing negative thermal expansion coefficients. The thermogravimetric analysis coupled with differential scanning calorimetry was also used to determine the optimal conditions to obtain a dense target in order to produce thin films by the Pulsed Laser Deposition (PLD) technique. Thin films elaborated under different oxygen pressures and temperatures exhibit a β-Cu2V2O7 polycrystalline phase and their band gap indicates absorption in the visible range. These oxides can be used as photoanodes and their photoelectrochemical properties were studied for both bulk (α-Cu2V2O7) and thin films (β-Cu2V2O7), as a function of the wavelength and/or intensity of the luminous flux. The best photocurrent efficiency was obtained under 450 nm illumination. Moreover, in the case of thin films, we have observed a linear evolution of the current density with the luminous flux. Finally, the photostability of thin films was measured and shows a reduction in the photocurrent of 8% after 1 h of measurement. This photocorrosion phenomenon was also highlighted by the elemental mapping performed on thin films by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectrometry (EDS).
References
More filters
TL;DR: In this paper, the Anderson theory of superexchange was extended to include spin-orbit coupling and the antisymmetric spin coupling suggested by Dzialoshinski from purely symmetry grounds and the symmetric pseudodipolar interaction were derived.
Abstract: A theory of anisotropic superexchange interaction is developed by extending the Anderson theory of superexchange to include spin-orbit coupling. The antisymmetric spin coupling suggested by Dzialoshinski from purely symmetry grounds and the symmetric pseudodipolar interaction are derived. Their orders of magnitudes are estimated to be ($\frac{\ensuremath{\Delta}g}{g}$) and ${(\frac{\ensuremath{\Delta}g}{g})}^{2}$ times the isotropic superexchange energy, respectively. Higher order spin couplings are also discussed. As an example of antisymmetric spin coupling the case of Cu${\mathrm{Cl}}_{2}$\ifmmode\cdot\else\textperiodcentered\fi{}2${\mathrm{H}}_{2}$O is illustrated. In Cu${\mathrm{Cl}}_{2}$\ifmmode\cdot\else\textperiodcentered\fi{}2${\mathrm{H}}_{2}$O, a spin arrangement which is different from one accepted so far is proposed. This antisymmetric interaction is shown to be responsible for weak ferromagnetism in $\ensuremath{\alpha}$-${\mathrm{Fe}}_{2}$${\mathrm{O}}_{3}$, MnC${\mathrm{O}}_{3}$, and Cr${\mathrm{F}}_{3}$. The paramagnetic susceptibility perpendicular to the trigonal axis is expected to increase very sharply near the N\'eel temperature as the temperature is lowered, as was actually observed in Cr${\mathrm{F}}_{3}$.
5,322 citations
TL;DR: In this paper, a thermodynamic theory of weak ferromagnetism of α-Fe 2 O 3, MnCO 3 and CoCO 3 is developed on the basis of landau's theory of phase transitions of the second kind.
Abstract: A thermodynamic theory of “weak” ferromagnetism of α-Fe 2 O 3 , MnCO 3 and CoCO 3 is developed on the basis of landau's theory of phase transitions of the second kind. It is shown that the “weak” ferromagnetism is due to the relativistic spin-lattice and the magnetic dipole interactions. A strong dependence of the properties of “weak” ferromagnetics on the magnetic crystalline symmetry is noted and the behaviour of these ferromagnetics in a magnetic field is studied.
4,730 citations
TL;DR: The discovery of ferroelectricity in a perovskite manganite, TbMnO3, where the effect of spin frustration causes sinusoidal antiferromagnetic ordering and gigantic magnetoelectric and magnetocapacitance effects are found.
Abstract: The magnetoelectric effect--the induction of magnetization by means of an electric field and induction of polarization by means of a magnetic field--was first presumed to exist by Pierre Curie, and subsequently attracted a great deal of interest in the 1960s and 1970s (refs 2-4). More recently, related studies on magnetic ferroelectrics have signalled a revival of interest in this phenomenon. From a technological point of view, the mutual control of electric and magnetic properties is an attractive possibility, but the number of candidate materials is limited and the effects are typically too small to be useful in applications. Here we report the discovery of ferroelectricity in a perovskite manganite, TbMnO3, where the effect of spin frustration causes sinusoidal antiferromagnetic ordering. The modulated magnetic structure is accompanied by a magnetoelastically induced lattice modulation, and with the emergence of a spontaneous polarization. In the magnetic ferroelectric TbMnO3, we found gigantic magnetoelectric and magnetocapacitance effects, which can be attributed to switching of the electric polarization induced by magnetic fields. Frustrated spin systems therefore provide a new area to search for magnetoelectric media.
3,769 citations
TL;DR: In this article, a review of mostly recent activities can be found, with a brief summary of the historical perspective of the multiferroic magnetoelectric composites since its appearance in 1972.
Abstract: Multiferroic magnetoelectric materials, which simultaneously exhibit ferroelectricity and ferromagnetism, have recently stimulated a sharply increasing number of research activities for their scientific interest and significant technological promise in the novel multifunctional devices. Natural multiferroic single-phase compounds are rare, and their magnetoelectric responses are either relatively weak or occurs at temperatures too low for practical applications. In contrast, multiferroic composites, which incorporate both ferroelectric and ferri-/ferromagnetic phases, typically yield giant magnetoelectric coupling response above room temperature, which makes them ready for technological applications. This review of mostly recent activities begins with a brief summary of the historical perspective of the multiferroic magnetoelectric composites since its appearance in 1972. In such composites the magnetoelectric effect is generated as a product property of a magnetostrictive and a piezoelectric substance. A...
3,288 citations
TL;DR: A striking interplay between ferroelectricity and magnetism in the multiferroic TbMn2O5 is reported, demonstrated by a highly reproducible electric polarization reversal and permanent polarization imprint that are both actuated by an applied magnetic field.
Abstract: Ferroelectric and magnetic materials are a time-honoured subject of study and have led to some of the most important technological advances to date. Magnetism and ferroelectricity are involved with local spins and off-centre structural distortions, respectively. These two seemingly unrelated phenomena can coexist in certain unusual materials, termed multiferroics1,2,3,4,5,6,7,8,9,10,11. Despite the possible coexistence of ferroelectricity and magnetism, a pronounced interplay between these properties has rarely been observed6,12. This has prevented the realization of multiferroic devices offering such functionality13. Here, we report a striking interplay between ferroelectricity and magnetism in the multiferroic TbMn2O5, demonstrated by a highly reproducible electric polarization reversal and permanent polarization imprint that are both actuated by an applied magnetic field. Our results point to new device applications such as magnetically recorded ferroelectric memory.
1,912 citations