The sensitivity of transport in colossal magnetoresistance (CMR) manganites to external electric and magnetic fields is examined using field effect configurations with La(0.7)Ca(0.3)MnO(3) (LCMO), Na(0.7)Sr(0.3)MnO(3), La(0.7)Ba(0.3)MnO(3), and La(0.5)Ca(0.5)MnO(3) (0.5-doped LCMO) channels, and ferroelectric PbZr(0.2)Ti(0.8)O(3) (PZT) or dielectric (SrTiO(3)) gates. A large electroresistance (ER) of approximately 76% at 4 x 10(5) V/cm is found in LCMO with PZT-ferroelectric gate, but the magnitude of the effect is much smaller (a few percent) in the other three channels. The ER and CMR effects are remarkably complimentary. The size and systematics of the effect strongly favor a percolative phase separation picture.

We present an experimental approach to study the ultrafast polarization switching dynamics in thin-film ferroelectrics. A semiconductor photoconductive switch with femtosecond laser illumination is used as a ''pulse generator'' to produce jitter-free, sub-100 ps rise time step-function-like electrical pulses. Quantitative measurements yield a polarization switching time, t s , of ϳ220 ps when measured with a 5 V, 68 ps rise time input electrical pulse. Modeling of the switching transients using the Merz-Ishibashi model and Merz-Shur model of switching kinetics yields a quantitative estimate of the characteristic switching time constant, t 0 , of ϳ70-90 ps.

We report on the epitaxial growth of wide-band-gap cubic-phase MgxZn1−xO thin films on Si(100) by pulsed-laser deposition and fabrication of oxide-semiconductor-based ultraviolet photodetectors. The challenges of large lattice and thermal expansion mismatch between Si and MgxZn1−xO have been overcome by using a thin SrTiO3 buffer layer. The heteroepitaxy of cubic-phase MgxZn1−xO on Si was established with epitaxial relationship of MgxZn1−xO(100)//SrTiO3(100)//Si(100) and MgxZn1−xO[100]//SrTiO3[100]//Si[110]. The minimum yield of the Rutherford backscattering ion channeling in MgxZn1−xO layer was only 4%, indicating good crystalline quality of the film. Smooth surface morphology with rms roughness of 0.6 nm was observed using atomic force microscopy. Photodetectors fabricated on Mg0.68Zn0.32O/SrTiO3/Si show peak photoresponse at 225 nm, which is in the deep UV region.

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We studied the effect of ion damage on the properties of 50 keV Ga+ focused ion beam fabricated lead-zirconate-titanate capacitors as a function of the ion dose. We observed significant modification in the chemical composition of the damaged layer due to loss of lead and oxygen, and gallium impurity accumulation. The 5–10 nm thick damaged layer becomes dielectric after annealing and does not recover its ferroelectric properties. This dielectric layer substantially reduces the actual volume of the ferroelectric material in sub-100 nm structures, and can affect their performance.