Multiferroics conventionally refer to the materials exhibiting co-existing electric, magnetic, and structure order parameters. Interplay between ferroelectricity, magnetism, and ferroelasticity in a ...single phase makes multiferroics truly multifunctional providing control over magnetic and electric ordering by applying electric and magnetic fields, respectively. Incorporation of multiferroic-based components into nanoscale applications will enable additional degrees of freedom in manipulating with spin and charge not easily attainable otherwise. Multiferroic bismuth ferrite lead titanate has been chemically synthesized in form of nanocrystalline films. The morphology of the films revealed a single perovskite phase confined within crystalline grains of few tens of nm in size. The films were found to exhibit ferroelectricity and ferromagnetism with characteristic electric polarization and magnetization hysteresis loops, transformations associated with spin reorientation in an external magnetic field and the spin-glassy behavior well above the room temperature. High degree of magnetic frustration and disorder in the spin system spatially confined in the nanograins, distribution of the grains anisotropy axis, inter-grain interactions, and the effects of uncompensated spins on the large effective surface/interface favored by the nanocrystalline morphology were assumed to be responsible for the anomalous magnetic properties and glassy dynamics in the films.
•First report on gas-phase palladium clusters deposited on self-assembled monolayers.•Comparison of metallization of four different self-assembled monolayers.•First report on metal coating of ...dithiocarbamates.
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A condensation-cell-type cluster aggregation source was used to deposit Pd clusters on the self-assembled monolayers of four different types of organic molecules. Mica slides covered by Au (111) were coated with self-assembled monolayer films of n-dodecanethiol, 4-mercaptopyridine, dimethyldithiocarbamate, and diethyldithiocarbamate, and the behaviour of Pd clusters on these surfaces, as well as on the bare Au (111) surface, was characterized using scanning tunnelling microscopy and X-ray photoelectron spectroscopy. The aim of this study was to present an alternative means for the metallization of organic layers, through the use of preformed clusters that, unlike single adatoms, are less likely to penetrate the organic layer and cause unwanted interfacial layers or short circuits, and deduce its suitability for the various types of organic self-assembled monolayers. Our experimental results indicate that all of the studied self-assembled monolayers are impenetrable for Pd clusters deposited at thermal energies. Contrary to most methods of metallization, Pd cluster deposition therefore provides an efficient means of growing metal overlayers on organic self-assembled monolayers.
While bulk gold is well known to be diamagnetic, there is a growing body of convincing experimental and theoretical work indicating that nanostructured gold can be imparted with unconventional ...magnetic properties. Bridging the current gap in experimental study of magnetism in bare gold nanomaterials, we report here on magnetism in gold nanocrystalline films produced by cluster deposition in the aggregate form that can be considered as a crossover state between a nanocluster and a continuous film. We demonstrate ferromagnetic-like hysteretic magnetization with temperature dependence indicative of spin-glass-like behavior and find this to be consistent with theoretical predictions, available in the literature, based on first-principles calculations.
•Bare nanostructured gold exhibits intrinsic ferro- and superparamagnetic behaviour.•Magnetic properties are strongly affected by the surface and size effects.•Interaction between clusters showing an ...core-shell structure causes magnetization.
Recent research has shown unconventional magnetic properties in nanosized gold systems. These effects have mostly been detected in functionalized gold nanoparticles as well as in gold nanocrystalline films. We demonstrate ferro- and superparamagnetic behaviour in assemblies of bare gold nanoclusters. This is demonstrated by the characteristic ferromagnetic hysteresis with the temperature dependent saturation magnetization, remanence and coercivity in aggregates of small clusters. The detected magnetization is caused by the interaction between the separate clusters exhibiting an core-shell structure, and dependent on the total amount of gold confined in the samples. The behaviour is analogous to that of transition metal clusters.
Sculpturing Nanowires with Ion Beams Tuboltsev, Vladimir; Räisänen, Jyrki
Small (Weinheim an der Bergstrasse, Germany),
December 4, 2009, Letnik:
5, Številka:
23
Journal Article
Recenzirano
Low‐energy, wide ion beams can be effectively used for gradual downsizing and shaping of prefabricated nanostructures in the sub‐50‐nm size regime (see image). A unique sculpturing capability ...exhibited by energetic ions on the nanometer scale enables mass production of continuous nanowires with an effective diameter of less than 10 nm.
Ion implantation of Fe and Mn into Al thin films was used for effective modification of Al superconductive properties. The critical temperature of the transition to the superconducting state was ...found to decrease gradually with implanted Fe concentration. It was found that suppression by Mn implantation is much stronger compared to Fe. At low concentrations of implanted ions, suppression of the critical temperature can be described with reasonable accuracy by existing models, while at concentrations above 0.1 at.% a pronounced discrepancy between the models and experiments is observed.
Preparation of nanocrystalline porous titanium dioxide (TiO
2) films with roll-to-roll compatible methods was studied. Gravure printing was used for spreading TiO
2 paste and paper calendering for ...pressing TiO
2 nanoparticle films. Influence of different preparation methods on performance of fabricated dye-sensitized solar cells (DSSCs) was investigated. The attained light into electricity conversion efficiency was compared with DSSCs fabricated on conductive plastic substrates by doctor-blading spreading with subsequent static pressing. The latter method achieved a light conversion efficiency as high as 5.1%. The efficiency of the cells with a gravure printed TiO
2 film was found to be rather low. The highest conversion efficiency was 1.7%; this is concluded to be due to insufficient thickness of the gravure printed TiO
2 films. Calendering of the doctor-bladed films on the other hand attained a light conversion efficiency of 4.7%.
Ion implantation of Fe and Mn into Al thin films was used for effective
modification of Al superconductive properties. Critical temperature of the
transition to superconducting state was found to ...decrease gradually with
implanted Fe concentration. it was found that suppression by Mn implantation
much stronger compared to Fe. At low concentrations of implanted ions,
suppression of the critical temperature can be described with reasonable
accuracy by existing models, while at concentrations above 0.1 at.% a
pronounced discrepancy between the models and experiments is observed.
Ion implantation of Fe and Mn into Al thin films was used for effective modification of Al superconductive properties. Critical temperature of the transition to superconducting state was found to ...decrease gradually with implanted Fe concentration. it was found that suppression by Mn implantation much stronger compared to Fe. At low concentrations of implanted ions, suppression of the critical temperature can be described with reasonable accuracy by existing models, while at concentrations above 0.1 at.% a pronounced discrepancy between the models and experiments is observed.
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