A phenomenological Landau theory for electromagnons in cubic spinel multiferroic CoCr<sub>2</sub>O<sub>4</sub>

Tiwari, Shruti; Sa, Debanand

doi:10.1088/0953-8984/22/22/225903

Cited by 8 publications

(3 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The unit cell of CoCr 2 O 4 consists of 32 oxygen, 16 chromium and 8 divalent transition metal ions. It is a ferrimagnetic (FiM) system that undergoes long range order at lock in temperature state at T F = 14 -15 K, spiral spin state at T s = 27 K and collinear short range FiM state at T c = 93-97 K. [7][8][9][10] Nanoparticle's surface spins play important role in controlling its magnetic properties for various applications and surface functionalization. 8,10 Due to magnetic nature of chromites, they have high tendency to agglomerate and one can get their collective magnetic response.…”

Section: Introductionmentioning

confidence: 99%

Role of SiO2 coating in multiferroic CoCr2O4 nanoparticles

et al. 2017

View full text Add to dashboard Cite

Effect of silica (SiO2) coating concentration on structural and magnetic properties of multiferroic cobalt chromite (CoCr2O4) nanoparticles have been studied. The nanoparticles with average crystallite size in the range 19 to 28 nm were synthesised by sol-gel method. X-ray diffraction (XRD) analysis has verified the composition of single-phase cubic normal spinel structure of CoCr2O4 nanoparticles. The average crystallite size and cell parameter decreased with increasing SiO2 concentration. TEM image revealed that the shape of nanoparticles was non-spherical. Zero field cooled/field cooled (ZFC/FC) curves revealed that nanoparticles underwent a transition from paramagnetic (PM) state to collinear short-range ferrimagnetic (FiM) state, and this PM–FiM transition temperature decreased from 101 to 95 K with increasing SiO2 concentration or decreasing crystallite size. A conical spin state at Ts = 27 K was also observed for all the samples which decreased with decreasing average crystallite size. Low temperature lock-in transition was also observed in these nanoparticles at 12 K for uncoated nanoparticles which slightly shifted towards low temperature with decreasing average crystallite size. Saturation magnetization (Ms) showed decreasing trend with increasing SiO2 concentration, which was due to decrease in average crystallite size of nanoparticles and enhanced surface disorder in smaller nanoparticles. The temperature dependent AC-susceptibility also showed the decrease in the transition temperature (Tc), broadening of the Tc peak and decrease in magnetization with increasing SiO2 concentration or decreasing average crystallite size. In summary, the concentration of SiO2 has significantly affected the structural and magnetic properties of CoCr2O4 nanoparticles.

show abstract

Section: Introductionmentioning

confidence: 99%

Role of SiO2 coating in multiferroic CoCr2O4 nanoparticles

et al. 2017

View full text Add to dashboard Cite

show abstract

“…The technological interest stems from the multifunctional properties exhibited by multiferroics, which make them potentially useful in device applications such as magnetoelectric memories and switches. Multiferroics are scientifically interesting, in part, because they exhibit a variety of microscopic mechanisms that can result in an interesting interplay between ferroelectric and magnetic orders; 2 among other consequences, this interplay can spawn interesting dynamical properties in multiferroic materials, including electromagnons, i.e., hybrid excitations involving a coupling between optical phonons and spin waves via the magnetoelectric interaction, [3][4][5][6][7][8][9][10][11][12][13][14] and magnetodielectric effects. [15][16][17] Materials in which geometric frustration leads to non-collinear spin order and strong spin-lattice coupling are particularly rich material environments to find novel magnetoelectric behavior.…”

Section: Introductionmentioning

confidence: 99%

Magnons and magnetodielectric effects in CoCr2O4 : Raman scattering studies

et al. 2017

View full text Add to dashboard Cite

Magnetoelectric materials have generated wide technological and scientific interest because of the rich phenomena these materials exhibit, including the coexistence of magnetic and ferroelectric orders, magnetodielectric behavior, and exotic hybrid excitations such as electromagnons. The multiferroic spinel material, CoCr2O4, is a particularly interesting example of a multiferroic material, because evidence for magnetoelectric behavior in the ferrimagnetic phase seems to conflict with traditional noncollinear-spin-driven mechanisms for inducing a macroscopic polarization. This paper reports an inelastic light scattering study of the magnon and phonon spectrum of CoCr2O4 as simultaneous functions of temperature, pressure, and magnetic field. Below the Curie temperature (TC ∼ 94 K) of CoCr2O4 we observe a ω ∼ 16 cm −1 q = 0 magnon having T1g-symmetry, which has the transformation properties of an axial vector. The anomalously large Raman intensity of the T1g-symmetry magnon is characteristic of materials with a large magneto-optical response and likely arises from large magnetic fluctuations that strongly modulate the dielectric response in CoCr2O4. The Raman susceptibility of the T1g-symmetry magnon exhibits a strong magnetic-field dependence that is consistent with the magnetodielectric response observed in CoCr2O4, suggesting that magnetodielectric behavior in CoCr2O4 primarily arises from the field-dependent suppression of magnetic fluctuations that are strongly coupled to long-wavelength phonons. Increasing the magnetic anisotropy in CoCr2O4 with applied pressure decreases the magnetic field-dependence of the T1g-symmetry magnon Raman susceptibility in CoCr2O4, suggesting that strain can be used to control the magnetodielectric response in CoCr2O4.

show abstract

“…1, 25,26 From the perspective of symmetry, 27 DyFeO3, have very low transition temperatures which renders them impractical. 28,29 Some room temperature antiferromagnetic-FE ME materials such as BiFeO3 are also studied by Ramesh 30 but the weak coupling effect in the systems is still a concern.…”

Section: Overview Of the Magnetoelectric Coupling Effect And Materialsmentioning

confidence: 99%

Synchrotron Investigations on La0.7Sr0.3MnO 3PbZr0.2Ti0.8O3 Heterostructures

Zhou¹

View full text Add to dashboard Cite

Synchrotron investigations on La 0.7 Sr 0.3 MnO 3 /PbZr 0.2 Ti 0.8 O 3 heterostructures Jinling Zhou This dissertation is devoted to understanding the La0.7Sr0.3MnO3 (LSMO)/ PbZr0.2Ti0.8O3 (PZT) magnetoelectric interface through synchrotron x-ray absorption and other techniques. The word magnetoelectric (ME) describes the coupling effects in certain materials that exhibit a change of the magnetic (electric) order with the change of the electric (magnetic) field. Materials that are ME could potentially advance current technology. Faster, more sensitive, and more energy efficient devices can be built with ME materials as compared to the present systems. Practical ME materials are essential for the realization of this advancement. Single phase ME materials are rare and the known few do not have strong coupling effects at ambient temperatures. Bilayer (or multilayer) systems, however, provide a feasible alternative because they sometimes exhibit ME coupling effects at the interface(s).

show abstract

A phenomenological Landau theory for electromagnons in cubic spinel multiferroic CoCr₂O₄

Cited by 8 publications

References 25 publications

Role of SiO2 coating in multiferroic CoCr2O4 nanoparticles

Role of SiO2 coating in multiferroic CoCr2O4 nanoparticles

Magnons and magnetodielectric effects in CoCr2O4 : Raman scattering studies

Synchrotron Investigations on La0.7Sr0.3MnO 3PbZr0.2Ti0.8O3 Heterostructures

Contact Info

Product

Resources

About

A phenomenological Landau theory for electromagnons in cubic spinel multiferroic CoCr2O4

Cited by 8 publications

References 25 publications

Role of SiO2 coating in multiferroic CoCr2O4 nanoparticles

Role of SiO2 coating in multiferroic CoCr2O4 nanoparticles

Magnons and magnetodielectric effects in CoCr2O4 : Raman scattering studies

Synchrotron Investigations on La0.7Sr0.3MnO 3PbZr0.2Ti0.8O3 Heterostructures

Contact Info

Product

Resources

About

A phenomenological Landau theory for electromagnons in cubic spinel multiferroic CoCr₂O₄