Riccardo Cucini is researcher at the SPRINT Laboratory high harmonic generation beamline.
He has many years of experience with femtosecond lasers, nonlinear spectroscopies and in the design and implementation of experimental setups for optical lasers and ultraviolet.
His research activity is focused on non-linear spectroscopy on condensed matter and time-resolved “pump and probe” spectroscopy based on table top and free electron lasers.
Evidence of Robust Half-Metallicity in Strained Manganite Films
G.M. Pierantozzi, G. Vinai, A.Y. Petrov, A. De Vita, F. Motti, V. Polewczyk, D. Mondal, T. Pincelli, R. Cucini, C. Bigi, I. Vobornik, J. Fujii, P. Torelli, F. Offi, G. Rossi, G. Panaccione, and F. Borgatti
We investigated the relationship between ferromagnetism and metallicity in strained La0.67Ca0.33MnO3 films grown on lattice-mismatched NdGaO3 (001) by means of spectroscopic techniques directly sensitive to the ferromagnetic state, to the band structure, and to the chemical state of the atoms. In this system, the ferromagnetic metallic (FMM) phase spatially coexists with an insulating one in most of the phase diagram. First, the observation of an almost 100% spin polarization of the photoelectrons at the Fermi level in the fundamental state provides direct evidence of the half-metallicity of the FMM phase, a result that has been previously observed through direct probing of the valence band only on unstrained, phase-homogeneous La0.67Sr0.33MnO3. Second, the spin polarization results to be correlated with the occupancy at the Fermi level for all the investigated temperature regimes. These outcomes show that the half-metallic behavior predicted by a double-exchange model persists even in phase-separated manganites. Moreover, the correlation between metallicity and ferromagnetic alignment is confirmed by X-ray magnetic circular dichroism, a more bulk-sensitive technique, allowing one to explain transport properties in terms of the conduction through aligned FMM domains.
From our users
Small, 17, 2100050, (2021)
Quantitative Ultrafast Electron-Temperature Dynamics in Photo-Excited Au Nanoparticles
M. Sygletou, S. Benedetti, M. Ferrera, G.M. Pierantozzi, R. Cucini, G. Della Valle, P. Carrara, A. De Vita, A. di Bona, P. Torelli, D. Catone, Gi. Panaccione, M. Canepa, F. Bisio
The femtosecond evolution of the electronic temperature of laser-excited gold nanoparticles is measured, by means of ultrafast time-resolved photoemission spectroscopy induced by extreme-ultraviolet radiation pulses. The temperature of the electron gas is deduced by recording and fitting high-resolution photo emission spectra around the Fermi edge of gold nanoparticles providing a direct, unambiguous picture of the ultrafast electron-gas dynamics. These results will be instrumental to the refinement of existing models of femtosecond processes in laterally-confined and bulk condensed-matter systems, and for understanding more deeply the role of hot electrons in technological applications.
Struct. Dyn., 7, 014303, (2020)
Coherent narrowband light source for ultrafast photoelectron spectroscopy in the 17–31 eV photon energy range
R. Cucini, T. Pincelli, G. Panaccione, D. Kopic, F. Frassetto, P. Miotti, G.M. Pierantozzi, S. Peli, A. Fondacaro, A. De Luisa, A. De Vita, P. Carrara, D. Krizmancic, D.T. Payne, F. Salvador, A. Sterzi, L. Poletto, F. Parmigiani, G. Rossi, and F. Cilento
Here, we report on a novel narrowband High Harmonic Generation (HHG) light source designed for ultrafast photoelectron spectroscopy (PES) on solids. Notably, at 16.9 eV photon energy, the harmonics bandwidth equals 19 meV. This result has been obtained by seeding the HHG process with 230 fs pulses at 515 nm. The ultimate energy resolution achieved on a polycrystalline Au sample at 40 K is ∼22 meV at 16.9 eV. These parameters set a new benchmark for narrowband HHG sources and have been obtained by varying the repetition rate up to 200 kHz and, consequently, mitigating the space charge, operating with ≈3×107 electrons/s and ≈5×108 photons/s. By comparing the harmonics bandwidth and the ultimate energy resolution with a pulse duration of ∼105 fs (as retrieved from time-resolved experiments on bismuth selenide), we demonstrate a new route for ultrafast space-charge-free PES experiments on solids close to transform-limit conditions.
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NFFA is a Progetto Internazionale financed by MIUR through CNR
(Istituto Officina dei Materiali, Trieste) and Elettra-Sincrotrone Trieste
and managed by the Commissione NFFA chaired by Giorgio Rossi
(Università di Milano and IOM-CNR).