A5052349501- Semiconductor Quantum Structures and Devices
- Photonic and Optical Devices
- Surface and Thin Film Phenomena
- Spectroscopy and Laser Applications
- Semiconductor materials and devices
- Graphene research and applications
- Nanowire Synthesis and Applications
- Advancements in Semiconductor Devices and Circuit Design
- Semiconductor materials and interfaces
- Surface Chemistry and Catalysis
- Magnetism in coordination complexes
- Quantum and electron transport phenomena
- Silicon Nanostructures and Photoluminescence
- Magnetic properties of thin films
- Molecular Junctions and Nanostructures
- Terahertz technology and applications
- Semiconductor Lasers and Optical Devices
- Electronic and Structural Properties of Oxides
- Advanced Chemical Physics Studies
- Vibrio bacteria research studies
- Atmospheric Ozone and Climate
- nanoparticles nucleation surface interactions
- Force Microscopy Techniques and Applications
- Carbon Nanotubes in Composites
- Thin-Film Transistor Technologies
University of Rome Tor Vergata
2009-2025
Roma Tre University
2018-2025
ETH Zurich
2014-2022
Marconi University
2021
University of Glasgow
2019-2021
University of Pisa
2021
Sapienza University of Rome
2021
National Interuniversity Consortium for the Physical Sciences of Matter
2014
Stable magnets from single atoms An important goal in molecular magnetism is to create a permanent magnet atom. Metal adsorbed on surfaces can develop strong magnetization an applied field (paramagnetism). Donati et al. show that holmium magnesium oxide film grown silver substrate residual for temperatures up 30 K and bistabilty lasts 1500 s at 10 (see the Perspective by Khajetoorians Heinrich). The atom avoids spin relaxation combination of quantum-state symmetry preventing interacting with...
We fabricated flat, two-dimensional germanium sheets showing a honeycomb lattice that matches of germanene by depositing submonolayers Ge on graphite at room temperature and subsequent annealing to 350 °C. Scanning tunneling microscopy shows the islands have small buckling with no atomic reconstruction does not give any hints for alloy formation hybridization substrate. Our density functional theory calculations structural properties agree well our experimental findings indicate sheet...
We investigate the spin relaxation of Ho single atom magnets on MgO/Ag(100) as a function temperature and magnetic field. find that is thermally activated at low field, while it remains larger than 1000 s up to 30 K 8 T. This behavior contrasts with molecule bulk paramagnetic impurities, which relax faster high Combining our results density functional theory, we rationalize this unconventional by showing local vibrations activate two-phonon Raman process rate peaks near zero field suppressed...
We report x-ray absorption spectroscopy and magnetic circular dichroism measurements as well multiplet calculations for Dy, Ho, Er, Tm atoms adsorbed on Pt(111), Cu(111), Ag(100), Ag(111). In the gas phase, all four elements are divalent we label their $4f$ occupancy $4{f}^{n}$. Upon surface adsorption, depending substrate, either remain in that state or become trivalent with $4{f}^{n\ensuremath{-}1}$ configuration. The is realized when sum of atomic correction energies...
We develop a generalized theory for the scattering process produced by interface roughness on charge carriers and which is suitable any semiconductor heterostructure. By exploiting our experimental insights into three-dimensional atomic landscape obtained Ge/GeSi heterointerfaces atom probe tomography, we have been able to define full set of parameters relevant potential, including both in-plane axial correlation inside real diffuse interfaces. Our findings indicate partial coherence along...
Single atom magnets offer the possibility of magnetic information storage in most fundamental unit matter. Identifying parameters that control stability their states is crucial to design novel quantum with tailored properties. Here, we use X-ray absorption spectroscopy show electronic configuration dysprosium atoms on MgO(100) thin films can be tuned by proximity metal Ag(100) substrate onto which MgO are grown. Increasing thickness from 2.5 9 monolayers induces a change 4f9 4f10. Hysteresis...
The threading dislocation density (TDD) in plastically relaxed Ge/Si(001) heteroepitaxial films is commonly observed to decrease progressively with their thickness due mutual annihilation. However, there exists a saturation limit, known as the geometrical beyond which further of TDD Ge film hindered. Here, we show that such limit can be overcome SiGe/Ge/Si heterostructures thanks beneficial role second interface. Indeed, ${\mathrm{Si}}_{0.06}{\mathrm{Ge}}_{0.94}/\mathrm{Ge}/\mathrm{Si}(001)$...
A complete description of Ge growth on vicinal Si(001) surfaces in the angular miscut range 0\ifmmode^\circ\else\textdegree\fi{}--8\ifmmode^\circ\else\textdegree\fi{} is presented. The key role substrate vicinality clarified from very early stages deposition up to nucleation 3D islands. By a systematic scanning tunneling microscopy investigation we are able explain competition between step-flow and 2D progressive elongation islands along direction [110]. Using finite element calculations,...
Ultrafast spin currents induced by femtosecond laser excitation of ferromagnetic metals have been found to contribute sub-picosecond demagnetization, and cause a transient enhancement the magnetization bottom Fe layer in Ni/Ru/Fe layered structure. We analyze ultrafast dynamics such structures element- time-resolved x-ray magnetic circular dichroism, for different Ni thicknesses, Ru Ta interlayers, varying pump fluence. While we do not observe discovered previously, find reduced...
Quantum cascade lasers are finicky, in terms of the structural quality active region, especially for strain-mismatched heterostructures like Ge/Si-Ge quantum wells. Accurate control electron-state coupling between well and barriers laser's different stages is crucial. This study shows how to produce high-quality asymmetric coupled $n$-type multiple wells carefully resonant tunneling through thicknesses, thus interwell wave-function hybridization. The set robust material parameters provided...
n-type Ge/SiGe terahertz quantum cascade lasers are investigated using non-equilibrium Green's functions calculations. We compare the temperature dependence of gain properties with an equivalent GaAs/AlGaAs laser design. In case, is found to be much more robust increase, enabling operation up room temperature. The better robustness respect III–V attributed weaker interaction optical phonons. effect lower interface quality and can partly overcome by engineering smoother confinement.
We report on the magnetic properties of Dy atoms adsorbed (001) surface SrTiO
Thick Ge/(Si,Ge) multiple-quantum-well heterostructures are interesting for silicon-integrated optoelectronic devices operating in the midinfrared and terahertz spectral regions. The epitaxy of such structures becomes increasingly challenging as their thickness increases, due to accumulation strain defects. This study proves that ultrahigh-vacuum chemical vapor deposition allows subnanometer control compositional profile throughout micrometer-thick strain-compensated multilayered with very...
Indium phosphide (InP) nanoislands are grown on pre-patterned Silicon (001) nanotip substrate using gas-source molecular-beam epitaxy via nanoheteroepitaxy approach. The study explores the critical role of growth temperature in achieving selectivity, governed by diffusion length. Our reveals that temperatures about 480 °C and lower, lead to parasitic growth, while 540 with an indium rate 0.7 Å.s−1 phosphine flux 4 sccm inhibit selective growth. establishment optimal window for InP is...
We investigated the reactivity of layered GeAs in presence oxygen or water using synchrotron-based X-ray photoelectron spectroscopy and ab initio calculations. By performing experiments at near-ambient pressure (up to 20 mbar), we gained detailed insights into material's stability under realistic conditions. showed limited with dry O2 deaerated H2O. However, a small amount humidity (Rw = 0.5% T °C) an atmosphere significantly enhanced reactivity. This synergistic effect was well captured by...
Abstract We use low-temperature scanning tunnelling microscopy (LT-STM) to characterize the early stages of silver fluorination. On Ag(100), we observe only one adsorbate species, which shows a bias-dependent STM topography. Notably, at negative bias voltages, VB < 0, apparent shape can be described as round protrusion surrounded by moat-like depression (sombrero). As voltage increases, changes, eventually evolving into depression. From images, determine adsorption site hollow position....
The long-term resistance to desiccation on abiotic surfaces is a key determinant of the adaptive success Acinetobacter baumannii as healthcare-associated bacterial pathogen. Here, cellular and molecular mechanisms enabling A. resist persist were investigated. Experiments set up mimic response air-drying that would occur when cells contaminate fomites in hospitals. Resistance transition "viable but nonculturable" (VBNC) state determined laboratory-adapted strain ATCC 19606T epidemic ACICU....
We report on the magnetic coupling between isolated Co atoms as well small islands and Ni(111) mediated by an epitaxial graphene layer. X-ray circular dichroism scanning tunneling microscopy combined with density functional theory calculations reveal that occupy two distinct adsorption sites, different to underlying surface. further a transition from antiferromagnetic ferromagnetic increasing cluster size. Our results highlight extreme sensitivity of exchange interaction site in-plane...
Starting with the basic definition, a short description of few relevant physical quantities playing role in growth process heteroepitaxial strained systems, is provided. As such, paper not meant to be comprehensive survey but present connection between Stranski-Krastanov mechanism nanostructure formation and principles nucleation growth. The elastic field described context continuum elasticity theory, using either analytical models or numerical simulations. results are compared selected...
The synthesis, spectroscopic, and optical properties of the water-soluble phosphorus complex a 2-sulfonato-10-(4-sulfonatophenyl)-5,15-dimesitylcorrole have been investigated. compound was prepared by adopting novel strategy for corrole sulfonation, leading to regioselective isomer in an almost quantitative yield. coordination has key role determining substitution pattern, limiting formation poly-substituted species, which affected reaction free base. resulting shows excellent terms emission...
Combining electron paramagnetic resonance (EPR) with scanning tunneling microscopy (STM) enables detailed insight into the interactions and magnetic properties of single atoms on surfaces. A requirement for EPR-STM is efficient coupling microwave excitations to tunnel junction. Here, we achieve a efficiency order unity by using radiofrequency antenna placed parallel STM tip, which interpret simple capacitive-coupling model. We further demonstrate possibility perform routinely above 4 K...