Two-dimensional graphene-based nanocomposite have gained much attention due to promising applications of electronic and optoelectronic devices. We report on the fabrication of c-axis oriented ZnO nanorods (NR) and ZnO (NR)...

Lead-free all oxide composite thin films comprising ferromagnetic (FM) and ferroelectric (FE) phases are observed as promising candidates for multifunctional device applications. A series of composites having systematic replacement of FM La0.67Sr0.33MnO3 (LSMO) by FE-Na0.5K0.5NbO3 (NKN), all oxide composite thin films were optimally grown by pulsed laser deposition. While x-ray diffraction confirmed a systematic phase change from a rhombohedral to an orthorhombic structure, almost monodispersed grain size distribution and smooth surface topography were revealed by atomic force microscopy. Two-probe dielectric spectroscopy indicated a pronounced enhancement of real permittivity for 0.4 sample as compared to the pure FM and FE parent compounds. Similarly, an enhancement in the magnetodielectric permittivity revealed high values for intermediate composites. The enhancement in the dielectric and magnetoelectric coupling is suggested to be due to the magnetostriction effect in FM (LSMO), which induces stress that is in turn transferred to the FE (NKN) phase, leading to strong FM–FE coupling. X-ray photoelectron spectroscopy reveals the presence of Mn in +3 and +4 states in the FE–FM composites. The presence of these mixed valence states can be ascribed to the magnetic properties within the composites.

Ca3CoMnO6, a quasi-1D Ising chain at low temperature offers rich fundamental physics and applications. We have studied the dielectric and magnetoelectric coupling in Fe doped Ca3CoMnO6 (CCMO) bulk ceramics prepared by co-precipitation technique. Single phase hexagonal crystal structure having R-3C space group was confirmed by x-ray diffraction. Extremely low currents were observed up to 20% Fe doping. Doping dependence of magnetoresistance (MR) revealed both positive and negative MR, with anomalously high MR values beyond 3000% in diluted Fe doped CCMO; whereas the higher doping of Fe was found to result in negative MR due to enhanced magnetostriction effects. The dielectric study was carried out for a range of 20 Hz to 10 MHz. The negative value of the colossal magnetodielectric induced in the Fe doped samples can be attributed to the magnetostriction effect along with interfacial Maxwell-Wagner polarization.

A nonvolatile memory effect exhibited by electric field-induced resistance switching has been the topic of intense research not only due to its applications as resistive random access memory but also from the basic physics point of view. Among several binary and ternary mixed oxide compounds, the ones which possess magnetic ions have shown a great promise. Spinel ferrite system Zn 0.3 Mn 0.7+x Si x Fe 2−2x O 4 with varying x is investigated for its novel electrical switching properties. Both temperature and applied voltage dependence of current-controlled negative resistance-type electrical switching showed better than 200% of resistive switching ratios. Bulk polycrystalline samples showed composition x dependence of resistive switching. The current-voltage characteristics are modeled for low and high applied field regime, and the presence of space-charge-limiting current is confirmed. Thin films of the ferrite system grown by pulsed laser deposition showed almost nonexistence of resistive switching, suggesting that the bulk composition of the compound has a major role to play against the film-electrode interface.

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