Elemental carbon represents a fundamental building block of matter and the possibility of ferromagnetic order in carbon attracted widespread attention. However, the origin of magnetic order in such a light element is only poorly understood and has puzzled researchers. We present a spectromicroscopy study at room temperature of proton irradiated metal free carbon using the elemental and chemical specificity of x-ray magnetic circular dichroism (XMCD). We demonstrate that the magnetic order in the investigated system originates only from the carbon π-electron system.

Sketch of the configuration of a light-controlled resistive switching memory. Light enters through the Al(2) O(3) uncovered surface and reaches the optically active p-Si substrate, where carriers are photogenerated and subsequently injected in the Al(2) O(3) layer when a suitable voltage pulse is applied. The resistance of the Al(2) O(3) can be switched between different non-volatile states, depending on the applied voltage pulse and on the illumination conditions.

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The influence of the Zn(2+) concentration and temperature on the electrochemical reduction of O(2) in a solution of zinc bis(trifluoromethanesulfonyl)imide (Zn(TFSI)(2)) salt in 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR(14)TFSI) ionic liquid is presented. ZnO nanocrystalline films were then electrodeposited, under enhanced O(2) reduction, at temperatures in the 75-150 °C range. Their morphology, chemical composition, structural and optical properties were analyzed. In contrast to the polar-oriented ZnO usually obtained from aqueous and conventional solvent based electrolytes, nanocrystalline films oriented along non-polar directions, (11 ̅10) and (11 ̅20), were obtained from this ionic liquid electrolyte. A significant content of carbon was detected in the films, pointing to the active participation and crucial effect of pyrrolidinium cation (and/or byproducts) during the electrodeposition. The films showed semiconducting behavior with an optical gap between 3.43 and 3.53 eV as measured by optical transmittance. Their room temperature photoluminescence spectra exhibited two different bands centered at ∼3.4 and ∼2.2 eV. The intensity ratio between both bands was found to depend on the deposition temperature. This work demonstrates the great potential of ionic liquids based electrolytes for the electrodeposition of ZnO nanocrystalline thin films with innovative microstructural and optoelectronic properties.