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We grow a range of cobalt-doped ZnO nanocrystals, form a monolayer through electrostatic assembly approach, and characterize the nanostructures with a scanning tunneling microscope tip. The scanning tunneling spectroscopy results show electrical bistability, that is, presence of a low- and a high-conducting state, in such monolayers under application of a voltage pulse. The bistability depends on the content of cobalt in the nanocrystals. With the use of such ferromagnetic nanocrystals, we align the magnetization vector of the nanocrystals in a monolayer in order to study the effect of alignment of their magnetic domains on the electrical bistability. We observe that the transport gap of the nanocrystals decreases upon conductance switching. The gap decreases also due to alignment of the magnetic domains of the cobalt-doped nanocrystals. When the magnetically aligned nanocrystals undergo a conductance switching, the transport gap further decreases evidencing a correlation between the electrical bistability and the (change in) transport gap. [ABSTRACT FROM AUTHOR]

The fields of photovoltaics, photodetection and light emission have seen tremendous activity in recent years with the advent of hybrid organic-inorganic perovskites. Yet, there have been far fewer reports of perovskite-based field-effect transistors. The lateral and interfacial transport requirements of transistors make them particularly vulnerable to surface contamination and defects rife in polycrystalline films and bulk single crystals. Here, we demonstrate a spatially-confined inverse temperature crystallization strategy which synthesizes micrometre-thin single crystals of methylammonium lead halide perovskites MAPbX3 (X = Cl, Br, I) with sub-nanometer surface roughness and very low surface contamination. These benefit the integration of MAPbX3 crystals into ambipolar transistors and yield record, room-temperature field-effect mobility up to 4.7 and 1.5 cm2 V−1 s−1 in p and n channel devices respectively, with 104 to 105 on-off ratio and low turn-on voltages. This work paves the way for integrating hybrid perovskite crystals into printed, flexible and transparent electronics. [ABSTRACT FROM AUTHOR]

Wemap band-edges across a pn-junction that was formed in a nanorod.We form a single junction between p-type Cu2S and n-typeCdS through a controlled cationic exchange process of CdS nanorods.We characterize nanorods of the individual materials and the singlejunction in a nanorod with an ultrahigh vacuum scanning tunnelingmicroscope (UHV-STM) at 77 K. From scanning tunneling spectroscopyand correspondingly the density of states (DOS) spectra, we determinethe conduction and valence band-edges at different points across thejunction and the individual nanorods. We could map the band-diagramof nanorod-junctions to bring out the salient features of a diode,such as p- and n-sections, band-bending, depletion region, albeitinterestingly in the nanoscale. [ABSTRACT FROM AUTHOR]

We formed magnetic moment assisted layer-by-layer (LbL)films ofa Prussian Blue analogue (PB). We applied an external magnetic fieldto each monolayer of PB to orient the magnetic moment of the compoundperpendicular to the substrate. Aligned moments or orientation ofthe magnetic compounds themselves were immobilized in each monolayer,so that the moments could augment formation of the subsequent monolayersof LbL adsorption process. We hence could form multilayered LbL filmsof PB molecules with their magnetic moments oriented perpendicularto the substrate. We also formed LbL films of the compound with theirmoments oriented parallel to the substrate and facing one particulardirection. We have measured conductivity and dielectric constant ofthe two types of films and compared the parameters with that of conventionalLbL films deposited without orienting magnetic moments of the molecules. [ABSTRACT FROM AUTHOR]

Abstract: We report effects of magnetic field on electrical bistability of ferromagnetic quantum dots. Here, we select Fe3O4 nanoparticles that can be magnetized. Devices based on such nanostructures exhibit conductance switching. Upon application of a magnetic field, the nature of electrical bistability changes completely. From the comparison of electrical characteristics without and with a magnetic field, we comment that magnetization and conductance-switching to a high-state occur concurrently. We also show how a transition between the two types of electrically-bistable characteristics occurs. The results show the viability of data-storage applications in quantum dots through magnetic field. [Copyright &y& Elsevier]