Significant Magnetoelectric Coupling Research Articles

Strong magnetoelectric coupling in highly oriented ZnO films deposited on Metglas substrates

AbstractWe have studied the magnetoelectric coupling in ZnO films deposited on Metglas substrates. Highly c‐axis oriented ZnO films were successfully deposited using pulsed laser deposition at a low temperature of 300 °C. High quality films with low surface roughness of 2.82 nm and thicknesses of about 2 μm were obtained. A large converse magnetoelectric coef‐ ficient of 3 × 10–6 s/m and a direct magnetoelectric coefficient of 47 mV/cm Oe at a low dc bias field of 17 Oe and frequency of 1 kHz were obtained by dynamic converse and direct magnetoelectric measurements, respectively. Our results demonstrate a significant magnetoelectric coupling in these layers. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Optical characterization ofBi2Se3in a magnetic field: Infrared evidence for magnetoelectric coupling in a topological insulator material

We present an infrared magneto-optical study of the highly thermoelectric narrow-gap semiconductor ${\text{Bi}}_{2}{\text{Se}}_{3}$. Far-infrared and midinfrared (IR) reflectance and transmission measurements have been performed in magnetic fields oriented both parallel and perpendicular to the trigonal $c$ axis of this layered material and supplemented with UV-visible ellipsometry to obtain the optical conductivity ${\ensuremath{\sigma}}_{1}(\ensuremath{\omega})$. With lowering of temperature we observe narrowing of the Drude conductivity due to reduced quasiparticle scattering, as well as an increase in the absorption edge due to direct electronic transitions. Magnetic fields $H\ensuremath{\parallel}c$ dramatically renormalize and asymmetrically broaden the strongest far-IR optical phonon, indicating interaction of the phonon with the continuum free-carrier spectrum and significant magnetoelectric coupling. For the perpendicular field orientation, electronic absorption is enhanced, and the plasma edge is slightly shifted to higher energies. In both cases the direct transition energy is softened in magnetic field.

The effect of magnetic nanoparticles on the morphology, ferroelectric, and magnetoelectric behaviors of CFO/P(VDF-TrFE) 0–3 nanocomposites

Multiferroic nanocomposite films composed of P(VDF-TrFE) copolymer and CoFe2O4 (CFO) nanoparticles have been prepared by a modified polymeric processing. Structural characterizations reveal that CFO nanoparticles with 80–100 nm diameters are well distributed in the P(VDF-TrFE) matrix. The crystalline and microstructure of P(VDF-TrFE) are strongly dependent on the volume fraction of CFO nanoparticles, which are further analyzed by Raman spectra. Consequently, the ferroelectric and magnetoelectric responses are strongly influenced by the concentration of CFO nanoparticles. A significant magnetoelectric coupling effect of around 40 mV/cm Oe is obtained from the nanocomposites. A relatively simple model has been adopted to calculate the magnetoelectric coefficient, which is also in agreement with the experimental results.

Magnetoelectric and dielectric relaxation properties of the high Curie temperature composite Sr1.9Ca0.1NaNb5O15–CoFe2O4

A magnetoelectric (ME) composite ceramic 0.6Sr1.9Ca0.1NaNb5O15–0.4CoFe2O4 (SCNN–CFO) was prepared by a conventional solid state reaction method. Remarkable dielectric constant dispersion with a Curie temperature of 270 °C was observed. This relaxor composite exhibits ferroelectric as well as ferrimagnetic hysteresis loops at room temperature. A significant ME coupling effect was observed. On the basis of our studies, it is demonstrated that the lead-free high Curie temperature SCNN–CFO relaxor composite material can be used in the future development of ME devices.