The multi phonon Raman scattering in Mn doped (1%–10%) ZnO was observed at room temperature using 514.5nm Ar+ laser. The additional optical modes at 327, 332, 482, 532, and 680cm−1 in Zn1−xMnxO targets were identified as the second order Raman modes in the disordered lattice and the precipitation of the secondary phase ZnMn2O4. The crystalline grain sizes of 1%, 3%, 5%, and 10% Mn doped ZnO samples were calculated by phonon confinement model as 31.8, 18.3, 15.9, and 14.1nm, respectively. The optical band gap was found to be increased (3.27–3.41eV) due to the Mn doping.

Enhanced magnetoelectric effect in La0.67Sr0.33MnO3/PbZr0.52Ti0.48O3 multiferroic nanocomposite films with a SrRuO3 buffer layer

PbZr 0.52 Ti 0.48 O 3 /La 0.67 Sr 0.33 MnO 3 (PZT/LSMO) bilayer with surface roughness ~ 1.8 nm thin films have been grown by pulsed laser deposition on LaAlO 3 (LAO) substrates. High remnant polarization (30-54μC/cm 2 ), dielectric constant(400-1700), and well saturated magnetization were observed depending upon the deposition temperature of the ferromagnetic layer and applied frequencies. Giant frequency-dependent change in dielectric constant and loss were observed above the ferromagnetic-paramagnetic temperature. The frequency dependent dielectric anomalies are attributed to the change in metallic and magnetic nature of LSMO and also the interfacial effect across the bilayer; an enhanced magnetoelectric interaction may be due to the Parish-Littlewood mechanism of inhomogeneity near the metal-dielectric interface.

Electric-field-dependent in situ Raman studies have been carried out on chemically prepared graphene oxide. The Raman spectra show significant changes with increase in the applied electric field; in particular, the intensity of the G peak decreases with electric field. This behavior is typical for chemically or thermally reduced graphene oxide. To understand the nature of reduction, we compared the temperature-dependent and electric-field-dependent Raman spectra of graphene oxide and found that the evolutions of Raman spectra are not in agreement with each other, except the intensity of the G peak that decreases in both cases. The D peak broadens significantly with increase in temperature, whereas it sharpens in the case of applied electric field. The electron-field-emission properties of the electrically reduced graphene oxide were also carried out, and the turn-on field was found to be 9.1 V/μm.

A.; Scott, J. F.; et al., "Room temperature multiferroic effects in superlattice nanocapacitors," Appl. Phys. Lett. 97, 252902 (2010); http:// dx