Tommaso Pincelli worked as a CNR-IOM Post-doc from November 2017 to September 2018.
He is currently working in the Structural & Electronic Surface Dynamics group at the Fritz Haber Institute of the Max Planck Society, Germany.
His research activity was focused on the study of the dynamical properties of magnetic hetero structures. In particular, he investigated the ultrafast dynamics of magnetization in metallic thin films under optical excitation. To this aim, he has been working at the development of SPRINT Laboratory, that allows to perform spin and time resolved photoemission exploiting a High-Harmonic-Generation source.
2017 - Ph.D. in Physics at the University of Milan, Italy
2014 - Master's Degree in Physics at the University of Modena and Reggio Emilia, Italy
2011 - Bachelor Degree at the University of Modena and Reggio Emilia, Italy
Phys. Rev. B, 100, 045118, (2019)
Transient quantum isolation and critical behavior in the magnetization dynamics of half-metallic manganites
T. Pincelli, R. Cucini, A. Verna, F. Borgatti, M. Oura, K. Tamasaku, H. Osawa, T.-L. Lee, C. Schlueter, S. Günther, C.H. Back, M. Dell’Angela, R. Ciprian, P. Orgiani, A. Petrov, F. Sirotti, V.A. Dediu, I. Bergenti, P. Graziosi, F. Miletto Granozio, Y. Tanaka, M. Taguchi, H. Daimon, J. Fujii, G. Rossi, and G. Panaccione
We combine time-resolved pump-probe magneto-optical Kerr effect and photoelectron spectroscopy experiments supported by theoretical analysis to determine the relaxation dynamics of delocalized electrons in half-metallic ferromagnetic manganite La1−xSrxMnO3. We observe that the half-metallic character of La1−xSrxMnO3 determines the timescale of both the electronic phase transition and the quenching of magnetization, revealing a quantum isolation of the spin system in double-exchange ferromagnets extending up to hundreds of picoseconds. We demonstrate the use of time-resolved hard x-ray photoelectron spectroscopy as a unique tool to single out the evolution of strongly correlated electronic states across a second-order phase transition in a complex material.
Nature Communications, 8, 16051, (2017)
Quantifying the critical thickness of electron hybridization in spintronics materials
T. Pincelli, V. Lollobrigida, F. Borgatti, A. Regoutz, B. Gobaut, C. Schlueter, T.-L. Lee, D.J. Payne, M. Oura, K. Tamasaku, A.Y. Petrov, P. Graziosi, F. Miletto Granozio, M. Cavallini, G. Vinai, R. Ciprian, C.H. Back, G. Rossi, M. Taguchi, H. Daimon, G. van der Laan and G. Panaccione
In the rapidly growing field of spintronics, simultaneous control of electronic and magnetic properties is essential, and the perspective of building novel phases is directly linked to the control of tuning parameters, for example, thickness and doping. Looking at the relevant effects in interface-driven spintronics, the reduced symmetry at a surface and interface corresponds to a severe modification of the overlap of electron orbitals, that is, to a change of electron hybridization. Here we report a chemically and magnetically sensitive depth-dependent analysis of two paradigmatic systems, namely La1−xSrxMnO3 and (Ga,Mn)As. Supported by cluster calculations, we find a crossover between surface and bulk in the electron hybridization/correlation and we identify a spectroscopic fingerprint of bulk metallic character and ferromagnetism versus depth. The critical thickness and the gradient of hybridization are measured, setting an intrinsic limit of 3 and 10 unit cells from the surface, respectively, for (Ga,Mn)As and La1−xSrxMnO3, for fully restoring bulk properties.
J. Synchrotron Rad., 24, 175-187, (2017)
Performance of photoelectron spin polarimeters with continuous and pulsed sources: from storage rings to free electron lasers
T. Pincelli, F. Grasselli, V.N. Petrov, P. Torelli and G. Rossi
In this work the experimental uncertainties concerning electron spin polarization (SP) under various realistic measurement conditions are theoretically derived. The accuracy of the evaluation of the SP of the photoelectron current is analysed as a function of the detector parameters and specifications, as well as of the characteristics of the photoexcitation sources. In particular, the different behaviour of single counter or twin counter detectors when the intensity fluctuations of the source are considered have been addressed, leading to a new definition of the SP detector performance. The widely used parameter called the figure of merit is shown to be inadequate for describing the efficiency of SP polarimeters, especially when they are operated with time-structured excitation sources such as free-electron lasers. Numerical simulations have been performed and yield strong implications in the choice of the detecting instruments in spin-polarization experiments, that are constrained in a limited measurement time. Our results are therefore applied to the characteristics of a wide set of state-of-the-art spectroscopy facilities all over the world, and an efficiency diagram for SP experiments is derived. These results also define new mathematical instruments for handling the correct statistics of SP measurements in the presence of source intensity fluctuations.
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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).