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By angle-resolved photoemission spectroscopy and polarization-dependent infrared reflectivity measurements the electronic and vibrational properties of the low-dimensional perovskites Sr1-yLayNbO3.5-x were studied along different crystal directions. The electronic behavior strongly depends on the oxygen and La content, including quasi-one-dimensional metallic and ferroelectric insulating behavior. An extremely small energy gap at the Fermi level is found for SrNbO3.41 and SrNbO3.45 along the conducting direction at low temperature, suggestive for a Peierls-type instability. Despite the similar nominal carrier density, for Sr0.8La0.2NbO3.50 the quasi-one-dimensional metallic character is suppressed and no gap opening is observed, which can be explained by differences in the crystal structure. Electron-phonon interaction appears to play ...
Resistive memory switching was investigated in titanates and niobates of the type A nB nO 3n+2 and in the high-T c superconductor Bi 2Sr 2CaCu 2O 8+δ. We studied the switching by current injection perpendicular to the layers. Both dc and pulsed measurements were performed. Out-of-plane transport properties were investigated by measurements of the resistance and current-voltage characteristics (IVs) vs. temperature for different resistive states. The critical temperature of superconducting transition and the critical current of intrinsic Josephson junctions were also analyzed for different resistive states in Bi 2Sr 2CaCu 2O 8+δ. The resistive memory switching was explained in terms of doping of the conducting layers, which is induced by trapped charges in the insulating layers. The charged insulating layers act as a floating gate and r...
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