In-plane current induced nonlinear magnetoelectric effects in single crystal films of barium hexaferrite.

This report is on the observation and analysis of nonlinear magnetoelectric effects (NLME) for in-plane currents perpendicularly to the hexagonal axis in single crystals and liquid phase epitaxy grown thin films of barium hexaferrite. Measurements involved tuning of ferromagnetic resonance (FMR) at 56-58 GHz in the multidomain and single domain states in the ferrite by applying a current. Data on the shift in the resonance frequency with input electric power was utilized to estimate the variations in the magnetic parameter that showed a linear dependence on the input electric power.

Nonlinear magnetoelectric effects in Al-substituted strontium hexaferrite.

This report is on the observation and theory of electric field E induced non-linear magnetoelectric (NLME) effects in single crystal platelets of ferrimagnetic M-type strontium aluminum hexagonal ferrite. Using microwave measurement techniques, it was found that a DC electric field along the hexagonal c-axis results in significant changes in the saturation magnetization and uniaxial magneto-crystalline anisotropy field and these changes are proportional to the square of the applied static electric field. The NLME effects were present with or without an external bias magnetic field.

Study of crystal-field excitations and infrared active phonons in TbMnO.

The Tb (4f ) crystal-field (CF) excitations and the infrared phonons in TbMnO are studied as a function of temperature and under an applied magnetic field. The phonon energy shifts reflect local displacement of the oxygen ions that contribute to the CF energy level shifts below 120 K and under magnetic field. The CF polarized transmission spectra provide interesting information about the debated nature of the excitations at 41, 65, 130 cm.

A comparative Raman study between PrMnO , NdMnO , TbMnO and DyMnO .

In this paper, we present a detailed Raman study of the non-multiferroic compounds PrMnO and NdMnO and the multiferroic compounds TbMnO and DyMnO as a function of temperature and magnetic field. All studied systems show anomalous phonon shifts close to the Néel transition T . In PrMnO and NdMnO , the frequency softenings are partly attributed to an orbital-spin-phonon coupling whereas in TbMnO and DyMnO , the relatively weak frequency shifts are rather attributed to an expansion of the Mn-O bond lengths.

Effect of laser pulse propagation on ultrafast magnetization dynamics in a birefringent medium.

Light propagation effects can strongly influence the excitation and the detection of laser-induced magnetization dynamics. We investigated experimentally and analytically the effects of crystallographic linear birefringence on the excitation and detection of ultrafast magnetization dynamics in the rare-earth orthoferrites (SmPr)FeO and (SmTb)FeO, which possess weak and strong linear birefringence, respectively. Our finding is that the effect of linear birefringence on the result of a magneto-optical pump-probe experiment strongly depends on the mechanism of excitation.