14 research outputs found
Balanced electron-hole transport in spin-orbit semimetal SrIrO3 heterostructures
Relating the band structure of correlated semimetals to their transport
properties is a complex and often open issue. The partial occupation of
numerous electron and hole bands can result in properties that are seemingly in
contrast with one another, complicating the extraction of the transport
coefficients of different bands. The 5d oxide SrIrO3 hosts parabolic bands of
heavy holes and light electrons in gapped Dirac cones due to the interplay
between electron-electron interactions and spin-orbit coupling. We present a
multifold approach relying on different experimental techniques and theoretical
calculations to disentangle its complex electronic properties. By combining
magnetotransport and thermoelectric measurements in a field-effect geometry
with first-principles calculations, we quantitatively determine the transport
coefficients of different conduction channels. Despite their different
dispersion relationships, electrons and holes are found to have strikingly
similar transport coefficients, yielding a holelike response under field-effect
and thermoelectric measurements and a linear, electronlike Hall effect up to 33
T.Comment: 5 pages, 4 figure
A Perspective on Recent Advances in Phosphorene Functionalization and its Application in Devices
Phosphorene, the 2D material derived from black phosphorus, has recently
attracted a lot of interest for its properties, suitable for applications in
material science. In particular, the physical features and the prominent
chemical reactivity on its surface render this nanolayered substrate
particularly promising for electrical and optoelectronic applications. In
addition, being a new potential ligand for metals, it opens the way for a new
role of the inorganic chemistry in the 2D world, with special reference to the
field of catalysis. The aim of this review is to summarize the state of the art
in this subject and to present our most recent results in preparation,
functionalization and use of phosphorene and its decorated derivatives. In
particular, we discuss several key points, which are currently under
investigation: the synthesis, the characterization by theoretical calculations,
the high pressure behaviour of black phosphorus, as well as decoration with
nanoparticles and encapsulation in polymers. Finally, device fabrication and
electrical transport measurements are overviewed on the basis of recent
literature and new results collected in our laboratories
Polymer-based black phosphorus (bP) hybrid materials by in situ radical polymerization: an effective tool to exfoliate bP and stabilize bP nanoflakes
Black phosphorus (bP) has been recently investigated for next generation
nanoelectronic multifunctional devices. However, the intrinsic instability of
exfoliated bP (the bP nanoflakes) towards both moisture and air has so far
overshadowed its practical implementation. In order to contribute to fill this
gap, we report here the preparation of new hybrid polymer-based materials where
bP nanoflakes exhibit a significantly improved stability. The new materials
have been prepared by different synthetic paths including: i) the mixing of
conventionally liquid-phase exfoliated bP (in DMSO) with PMMA solution; ii) the
direct exfoliation of bP in a polymeric solution; iii) the in situ radical
polymerization after exfoliating bP in the liquid monomer (methyl methacrylate,
MMA). This last methodology concerns the preparation of stable suspensions of
bPn-MMA by sonication-assisted liquid phase exfoliation (LPE) of bP in the
presence of MMA followed by radical polymerization. The hybrids characteristics
have been compared in order to evaluate the bP dispersion and the effectiveness
of the bPn interfacial interactions with polymer chains aimed at their
long-term environmental stabilization. The passivation of bPn results
particularly effective when the hybrid material is prepared by in situ
polymerization. By using this synthetic methodology, the nanoflakes, even if
with a gradient of dispersion (size of aggregates), preserve their chemical
structure from oxidation (as proved by both Raman and 31P-Solid State NMR
studies) and are particularly stable to air and UV light exposure
Enhanced ambient stability of exfoliated black phosphorus by passivation with nickel nanoparticles
Since its discovery, the environmental instability of exfoliated black phosphorus (2D bP) has emerged as a challenge that hampers its wide application in chemistry, physics, and materials science. Many studies have been carried out to overcome this drawback. Here we show a relevant enhancement of ambient stability in few-layer bP decorated with nickel nanoparticles as compared to pristine bP. In detail, the behavior of the Ni-functionalized material exposed to ambient conditions in the dark is accurately studied by Transmission Electron Microscopy (TEM), Raman Spectroscopy, and high resolution x-ray Photoemission and Absorption Spectroscopy. These techniques provide a morphological and quantitative insight of the oxidation process taking place at the surface of the bP flakes. In the presence of Ni nanoparticles (NPs), the decay time of 2D bP to phosphorus oxides is more than three time slower compared to pristine bP, demonstrating an improved structural stability within 20 months of observation
Nanopatterning process based on epitaxial masking for the fabrication of electronic and spintronic devices made of La0.67Sr0.33MnO3/LaAlO3/SrTiO3 heterostructures with in situ interfaces
The fabrication of oxide electronics devices is presently hindered by the lack of standardized and well established patterning procedures, applicable down to the nanoscale. In this work, the authors propose a procedure to obtain patterns with resolution around 100 nm on (La,Sr)MnO3/LaAlO3/SrTiO3 heterostructures. Our method is based on a multistep technique, which includes wet and dry etching, epitaxial masking, and e-beam lithography. Our procedure is devised to define independent patterns on the interfacial two dimensional electron gas and on the metallic top electrode, while preserving an all-in situ approach for the heterostructure growth. The authors show results on nanoscale devices based on (La,Sr)MnO3/LaAlO3/SrTiO3, suitable for oxide spintronics applications