Matteo Savoini


Last Name

Savoini

First Name

Matteo

ORCID

0000-0002-7418-5242

Organisational unit

03920 - Johnson, Steven / Johnson, Steven

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2022 - 202519
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Publications 1 - 10 of 19
  • Coherent manipulation of the effective mass via phonon excitation in the compensated semimetal WTe2
    Item type: Other Conference Item
    Savoini, Matteo; Beaud, P.; Cilento, Federico; et al. (2023)
  • Magnetoelectrics and Multiferroics: Theory, Synthesis, Characterisation, Preliminary Results and Perspectives for All-Optical Manipulations
    Item type: Review Article
    Bossini, Davide; Juraschek, Dominik; Geilhufe, Matthias; et al. (2023)
    Journal of Physics D: Applied Physics
    Solid state compounds exhibiting multiple and coupled macroscopic orders, named multiferroics, represent a challenge for both theoretical and experimental modern condensed-matter physics. Spins and the electric polarisation in conventional magnetic and ferroelectric materials can be manipulated on their fundamental timescales, by means of femtosecond laser pulses. In view of the resounding success and popularity of the all-optical approach, it is only natural to wonder about the application of this scheme to study the intrinsic coupling between spins and charges in multiferroics. Deeply fundamental questions arise: can ultrashort laser pulses deterministically activate, enhance or suppress the magnetoelectric coupling on the femtosecond timescale? Can these processes be triggered in a fully coherent fashion, thus being unrestrained by any thermal load? Which mechanism of spin-charge coupling is most favourable to overcome these overarching and daunting challenges? This problem is interdisciplinary in nature, requiring contributions from materials science and condensed matter physics from both theoretical and experimental perspectives. High-quality materials suitable for optical investigations have to be identified, synthetized and characterised. General and valid models offer then a guide to the plethora of possible light-induced processes, resulting in the desired ultrafast multiferroic manipulations. Finally, healthy experimental schemes, able to unambiguously track the ultrafast dynamics of either the ferroelectric or the magnetic order parameter have to be developed and implemented. Our motivation to write this review is to lay a broad and multidisciplinary foundation, which may be employed as a starting point for non-equilibrium approaches to the manipulation of the multiferroicity on the femtosecond timescale. This was also one of the main goals of the COST Action MAGNETOFON, whose network constitutes the core of the authors of this review. The present work thus represents a part of the scientific legacy of MAGNETOFON itself.
  • Unveiling Low THz Dynamics of Liquid Crystals: Identification of Intermolecular Interaction among Intramolecular Modes
    Item type: Journal Article
    Friebel, Patrick; Galimberti, Daria Ruth; Savoini, Matteo; et al. (2024)
    The Journal of Physical Chemistry B
    Liquid crystals have found a wide area of application over the last few decades, proving to be excellent materials for tunable optics from visible to near-infrared frequencies. Currently, much effort is devoted to demonstrating their applicability at THz frequencies (1–10 THz), where tremendous advances of broadband and intense sources have been achieved. Yet, a detailed understanding of THz-triggered dynamics in liquid crystals is incomplete. Here, we perform broadband THz time domain spectroscopy on 4-cyano-4′-alkyl-biphenyl (nCB) and 5-phenylcyclohexanes (PCH5) across mesophases. Density functional theory calculations on isolated molecules capture the majority of the response. In particular, the pronounced modes around 4.5 and 5.5 THz mainly originate from bending modes of the cyano group. In contrast, the broad response below 3 THz, linked to modes of the alkyl chain, disagrees with the single molecule calculation. Here, we identify a clear intermolecular character of the response, supported by dimer and trimer calculations.
  • Nonlinear Phonon Dynamics in Ferroelectric Germanium Telluride via Double Pump Excitation
    Item type: Conference Poster
    Ovuka, Vladimir; Savoini, Matteo; Abreu, Elsa; et al. (2022)
  • Roles of band gap and Kane electronic dispersion in the THz-frequency nonlinear optical response in HgCdTe
    Item type: Conference Poster
    Soranzio, Davide; Abreu, Elsa; Houver, Sarah; et al. (2024)
  • Towards the epitaxial growth of Au thin films on MgO substrates for plasmonic applications
    Item type: Journal Article
    Celebrano, Michele; Savoini, Matteo; Biagioni, Paolo; et al. (2024)
    Journal of the European Optical Society-Rapid Publications
    Surface Plasmon Polaritons (SPPs) in Au thin films are nowadays intensively exploited for sensing applications that leverage the strong optical field confinement at the metal/dielectric interface and the easy functionalization of the Au surface. Moreover, Au thin films represent one of the common starting points for the top-down nanofabrication of plasmonic nanostructures supporting localized resonances. In this framework, strategies for the growth of high-quality Au films on transparent substrates are crucial and not yet fully established. In this study, we exploit MgO(001) substrates for the growth of thin (about 45 nm) Au films, also including an additional buffer layer of Fe. We successfully demonstrate Au samples with reduced roughness and presenting Low-Energy Electron Diffraction (LEED) features, indicating a high degree of crystalline ordering. This is supported by the experimental evidence of an increased (by almost a factor of 3) propagation length compared to a reference Au sample grown on standard glass slides, which is however still significantly lower than the one expected from first principles.
  • Non-equilibrium dynamics of spin-lattice coupling
    Item type: Journal Article
    Ueda, Hiroki; Mankowsky, Roman; Paris, Eugenio; et al. (2023)
    Nature Communications
    Quantifying the dynamics of normal modes and how they interact with other excitations is of central importance in condensed matter. Spin-lattice coupling is relevant to several sub-fields of condensed matter physics; examples include spintronics, high-Tc superconductivity, and topological materials. However, experimental approaches that can directly measure it are rare and incomplete. Here we use time-resolved X-ray diffraction to directly access the ultrafast motion of atoms and spins following the coherent excitation of an electromagnon in a multiferroic hexaferrite. One striking outcome is the different phase shifts relative to the driving field of the two different components. This phase shift provides insight into the excitation process of such a coupled mode. This direct observation of combined lattice and magnetization dynamics paves the way to access the mode-selective spin-lattice coupling strength, which remains a missing fundamental parameter for ultrafast control of magnetism and is relevant to a wide variety of materials.
  • Temperature- and field-dependent nonlinear 2D THz response in Hg1-xCdxTe
    Item type: Conference Poster
    Soranzio, Davide; Abreu, Elsa; Dössegger, Janine; et al. (2022)
  • THz-induced carrier multiplication in TaAs Weyl semimetal
    Item type: Conference Paper
    Houver, Sarah; Soranzio, Davide; Biasco, Simone; et al. (2023)
    2023 48th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)
    Topological Dirac and Weyl semimetals (D&W SM) have attracted a lot of attention due to their unusual electronic properties, which are strongly dependent on the symmetry of the system. By altering the symmetry of the lattice, using for example a pulse of light, one can expect to modify their topological nature and induce/suppress the related properties "on demand". High-field Terahertz (THz) radiation that interacts with vibrational states under near-resonant conditions is a promising pump candidate to induce structural changes in D& W SM compounds, possibly leading to topological transient or permanent changes. There are, however, some challenges to achieving such control. D&W SM have a specific band structure showing a 3D-linear dispersion around nodes, which makes them sensitive to THz-induced carrier multiplication. These carrier multiplication processes can compete with and ultimately screen the interaction of the THz light with vibrational modes. Here, we present recent results of 2D-THz spectroscopy of a bulk Weyl semimetal TaAs in reflection. We highlight THz-induced carrier multiplication effects and study the field and temperature dependence of the number of carriers induced by the THz field. We examine possible carrier multiplication mechanisms which could be involved.
  • Roles of band gap and Kane electronic dispersion in the THz-frequency nonlinear optical response in HgCdTe
    Item type: Other Conference Item
    Soranzio, Davide; Abreu, Elsa; Houver, Sarah; et al. (2024)
Publications 1 - 10 of 19