A5067064915- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Advanced Chemical Physics Studies
- Electronic and Structural Properties of Oxides
- Perovskite Materials and Applications
- Magnetic and transport properties of perovskites and related materials
- Spectroscopy and Quantum Chemical Studies
- Thermal properties of materials
- Mechanical and Optical Resonators
- High-pressure geophysics and materials
- Advanced Memory and Neural Computing
- nanoparticles nucleation surface interactions
- Transition Metal Oxide Nanomaterials
- Thermal Radiation and Cooling Technologies
- Electron and X-Ray Spectroscopy Techniques
- Mass Spectrometry Techniques and Applications
- Spectroscopy and Laser Applications
- Surface and Thin Film Phenomena
- 2D Materials and Applications
- Acoustic Wave Resonator Technologies
- Machine Learning in Materials Science
- Acoustic Wave Phenomena Research
- Iron-based superconductors research
- Photoreceptor and optogenetics research
- Ion-surface interactions and analysis
Università Cattolica del Sacro Cuore
2015-2024
National Institute of Optics
2024
University of Brescia
2012-2022
Elettra-Sincrotrone Trieste S.C.p.A.
2006
Istituto Nazionale per la Fisica della Materia
2003-2005
Sapienza University of Rome
1989
In the last two decades non-equilibrium spectroscopies have evolved from avant-garde studies to crucial tools for expanding our understanding of physics strongly correlated materials. The possibility obtaining simultaneously spectroscopic and temporal information has led insights that are complementary (and in several cases beyond) those attainable by studying matter at equilibrium. From this perspective, multiple phase transitions new orders arising competing interactions benchmark examples...
Unveiling the nature of bosonic excitations that mediate formation Cooper pairs is a key issue for understanding unconventional superconductivity. A fundamen- tal step toward this goal would be to identify relative weight electronic and phononic contributions overall frequency (\Omega) dependent function, \Pi(\Omega). We perform optical spectroscopy on Bi2212 crystals with simultaneous time- frequency-resolution; technique allows us disentangle by their different temporal evolution. The...
Superconductivity and charge density waves (CDWs) are competitive, yet coexisting, orders in cuprate superconductors. To understand their microscopic interdependence, a probe capable of discerning interaction on its natural length time scale is necessary. We use ultrafast resonant soft x-ray scattering to track the transient evolution CDW correlations YBa2Cu3O6+x after quench superconductivity by an infrared laser pulse. observe nonthermal response order characterized near doubling...
We study the photoinduced insulator-metal transition in VO2, correlating its threshold and dynamics with excitation wavelength. In single crystals, switching can only be induced photon energies above 670meV gap. This contrasts case of polycrystalline films, where formation metallic state initiated also as low 180meV, which are well below bandgap. Perfection this process may become conducive to schemes for optical switches, limiters, detectors operating at room temperature mid-infrared.
In strongly correlated systems the electronic properties at Fermi energy (EF) are intertwined with those high-energy scales. One of pivotal challenges in field high-temperature superconductivity (HTSC) is to understand whether and how scale physics associated Mott-like excitations (|E−EF|>1 eV) involved condensate formation. Here, we report interplay between many-body CuO2 1.5 2 eV, onset HTSC. This revealed by a novel optical pump-supercontinuum-probe technique that provides access dynamics...
The ultrafast thermal and mechanical dynamics of a two-dimensional lattice metallic nanodisks has been studied by near-infrared pump-probe diffraction measurements over temporal range spanning from $100\phantom{\rule{0.3em}{0ex}}\mathrm{fs}$ to several nanoseconds. experiments demonstrate that in these systems surface acoustic wave (SAW), with vector given the reciprocal periodicity array, can be excited $\ensuremath{\sim}120\phantom{\rule{0.3em}{0ex}}\mathrm{fs}$ Ti:sapphire laser pulses....
The temperonic crystal, a periodic structure with unit cell made of two slabs sustaining temperature wave-like oscillations on short time-scales, is introduced. complex-valued dispersion relation for the scalar field investigated case localised pulse. discloses frequency gaps, tunable upon varying thermal properties. Results are shown paradigmatic graphene-based crystal. crystal extends concept superlattices to realm waves, allowing coherent control ultrafast pulses in hydrodynamic regime at...
In this letter we demonstrate the possibility to determine temporal and spectral structure (spectrogram) of a complex light pulse exploiting ultrafast switching character nonthermal photoinduced phase transition. As proof, use VO2 multifilm, undergoing an insulator-to-metal transition when excited by femtosecond near-infrared laser pulses. The abrupt variation in multifilm optical properties, over broad infrared/visible frequency range, is exploited determine, situ simple way, spectrogram...
Photoinduced phase transitions from insulating to metallic states, accompanied by structural re-arrangements, have been recently reported in complex transition-metal oxides. However, the optical control of a purely electronic transition, where thermodynamic is determined distribution excitations, has remained elusive. Here we report an underdoped Bi2212 crystal through impulsive photoinjection quasiparticles (QP) via ultrashort laser pulses, avoiding significant heating. An abrupt transition...
We present a theoretical framework allowing to properly address the nature of surfacelike eigenmodes in hypersonic surface phononic crystal, composite structure made periodic metal stripes nanometer size and periodicity $1\text{ }\ensuremath{\mu}\text{m}$, deposited over semi-infinite silicon substrate. In surface-based crystals there is no distinction between periodically nanostructured overlayer acoustic modes substrate, solution elastic equation being pseudosurface wave partially...
Here we report extensive ultrafast time-resolved reflectivity experiments on overdoped Bi${}_{2}$Sr${}_{2}$Ca${}_{1\ensuremath{-}x}$Y${}_{x}$Cu${}_{2}$O${}_{8+\ensuremath{\delta}}$ single crystals ($T$${}_{c}=78$ K) aimed to clarify the nature of superconducting-to-normal-state photoinduced phase transition. The data show a lack quasiparticle decay time divergence at fluence required induce this transition, in contrast thermally driven transition observed $T$${}_{c}$ and variance with...
A major challenge in understanding the cuprate superconductors is to clarify nature of fundamental electronic correlations that lead pseudogap phenomenon. Here we use ultrashort light pulses prepare a non-thermal distribution excitations and capture novel properties are hidden at equilibrium. Using broadband (0.5-2 eV) probe, able track dynamics dielectric function unveil an anomalous decrease scattering rate charge carriers pseudogap-like region temperature (T) hole-doping (p) phase...
A design for photoacoustic mass sensors operating above 100 GHz is proposed. The based on impulsive optical excitation of a pseudosurface acoustic wave in surface phononic crystal with nanometric periodic grating and time-resolved extreme ultraviolet detection the frequency shift upon loading device. present opens path to range currently unaccessible electro-acoustical transducers, providing enhanced sensitivity, miniaturization, incorporating time-resolving capability while forgoing...
Ultrafast broadband transient reflectivity experiments are performed to study the interplay between non-equilibrium dynamics of pseudogap and superconducting phases in Bi$_{2}$Sr$_{2}$Ca$_{0.92}$Y$_{0.08}$Cu$_{2}$O$_{8+\delta}$. Once superconductivity is established relaxation proceeds $\sim$ 2 times faster than normal state, corresponding variation changes sign after 0.5 ps. The results can be described by a set coupled differential equations for order parameter. strength coupling term...
Ultrathin metal nanoparticles coatings, synthesized by gas-phase deposition, are emerging as go-to materials in a variety of fields ranging from pathogens control and sensing to energy storage. Predicting their morphology mechanical properties beyond trial-and-error approach is crucial issue limiting exploitation real-life applications. The Ag nanoparticle ultrathin films, supersonic cluster beam here assessed adopting bottom-up, multitechnique approach. A virtual film model proposed merging...
The morphological and mechanical properties of nanoparticles-based ultrathin Ag films, synthesized by supersonic cluster beam deposition over a sapphire substrate, are unveiled exploiting ultrafast optoacoustic, atomic force microscopy, X-ray photoelectron spectroscopies, diffraction techniques. with thicknesses in the 10–50 nm range, have porous structure composed metallic nanoparticles crystalline average diameter 6 nm. films acoustic modes hypersonic frequency thinner frequencies...
Many puzzling properties of high-$T_c$ superconducting (HTSC) copper oxides have deep roots in the nature antinodal quasiparticles, elementary excitations with wavevector parallel to Cu-O bonds. These electronic states are most affected by onset antiferromagnetic correlations and charge instabilities they host maximum anisotropic gap pseudogap. In this work, we use time-resolved extreme-ultra-violet (EUV) photoemission proper photon energy (18 eV) time-resolution (50 fs) disclose ultrafast...
Unveiling the physics that governs intertwining between nanoscale self-organization and dynamics of insulator-to-metal transitions (IMTs) is key for controlling on demand ultrafast switching in strongly correlated materials nanodevices. A paradigmatic case IMT ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$, which mechanism leads to nucleation growth metallic nanodroplets out supposedly homogeneous Mott insulating phase still a mystery. Here, we combine x-ray photoemission electron microscopy...
Abstract Mott transitions in real materials are first order and almost always associated with lattice distortions, both features promoting the emergence of nanotextured phases. This nanoscale self-organization creates spatially inhomogeneous regions, which can host protect transient non-thermal electronic states triggered by light excitation. Here, we combine time-resolved X-ray microscopy a Landau-Ginzburg functional approach for calculating strain real-space configurations. We investigate...
The light-mediated interaction of fermionic and bosonic excitations governs the optoelectronic properties condensed matter systems. In photoexcited semiconductors, coupling electron–hole pairs (excitons) to coherent optical phonons enables a modulation excitonic resonance that is phase-locked frequency coupled vibrational mode. Moreover, due Coulombic nature excitons, their dynamics are sensitive transient changes in screening by carriers. Interestingly, effect photoinduced on signal...