323,212 research outputs found
Take home messages
No full textIn this final chapter we present some ‘take home message’. We set out what we believe are some of the most important learnings to have emerged to date from Finding a Voice, and some of their implications. \u
S. Marotta, Gli anni della pazienza. Bea, l'ecumenismo e il Sant'Uffizio di Pio XII, Bologna 2020
No full textRecensione in rivist
Le jésuite Pietro Tacchi Venturi et la persécution antijuive en Italie (1938-1943)
No full textThe article examines Jesuit Pietro Tacchi Venturi’s role in addressing aid appeals submitted to both him and the Holy See during World War II from Jews and Jewish converts to Catholicism. The article is divided into two parts. First, after a biographical overview of Tacchi Venturi, Sergio Palagiano presents Affari series documents about aid requests to escape racial laws that the Jesuit received for relevant fascist ministry handling. Second, Raffaella Perin reviews historiographical insights on Tacchi’s stance toward Jews and Italy’s racial laws. Using newly accessible documentation cross-referencing Vatican and Society of Jesus archives, she reconstructs various aid appeal cases
Stratigrafia, analisi di facies, paleogeografia ed inquadramento regionale del Giurassico dell'area dei Tacchi (Sardegna centro-orientale)
No full textNew investigations carried on the Jurassic successions of the
Tacchi area (Eastern Sardinia) have given a more detailed knowledge
of the local stratigraphy and sedimentology. Geological mapping
and litho-sedimentological analysis heve provided a detailed
framework for the vertical and areal development and evolution of
the sedimentary facies, and also allowed an accurate paleogeographical
construction. The Genna Selole Fm. (Bajocian-Bathonian)
(DIENI et alii, 1983), constituting the base of the Tacchi Jurassic succession,
is built of siliciclastic to mixed, siliciclastic-carbonate,
deposits. It was laid down in depositional environments ranging
from distal alluvial fan to transitional lagoonal-littoral. In places the
Genna Selole is absent and so the marine Dorgali Dolostones Fm.
(Bathonian-Kimmeridgian) (DIENI et alii, 1983), directly overlies the
folded Paleozoic basement. The omission of the Genna Selole Fm.
suggests the presence of uplifted areas of erosion and alteration
whose location has been controlled by structural, syn-depositional
factors, as a possible Variscan paleo-high. Based on new evidence,
the Genna Selole Fm. has been subdivided into three lithofacies: A) a
conglomeratic lithofacies (Laconi-Gadoni Lithofacies); B) a sandyclayey
lithofacies (Nurri-Escalaplano Lithofacies); and a mixed siliciclastic-
carbonate lithofacies (Ussassai-Perdasdefogu Lithofacies),
this latter constituting the gradual passage to the following Dorgali
Dolostones Fm. In addition, features observed in the Genna Selole
Fm. (slumps, synsedimentary faults, neptunian dykes, seismic breccias)
suggest active coeval extensional tectonics. The thickness of the
Genna Selole Fm. is between 0 and 50 m. We propose two others
additional parastratotypes for this formation in the Escalaplano and
Perdasdefogu areas, characterized by good continuity and exposure,
and so integrating the stratotype described by DIENI et alii (1983).
The comprehensive analysis of the Genna Selole Fm. isopachs and of
its lithofacies in the Tacchi area evidences the presence, and the subsequent
gradual burial and flooding, of a morpho-structural high («alto morfostrutturale barbaricino») developed in Central Sardinia,
due to the coeval extensional tectonics prevailing during the Lower
and Middle Jurassic. The upper Dorgali Dolostones Fm., up to 250-
300 m thick, is characterized by different lithofacies all referable to
inter- to subtidal environments of a carbonate shelf (stromatolitic
mounds, lagoonal sediments, storm layers, flaser bedding, herringbone
cross stratification, oolitic shoals and bars, possible internal
breccias of tectonic origin), extending between the carbonate lagoon
and the platform break. The most widespread deposits are irregular
alternations of calcarenitic storm layers and bioturbated mudstones.
In the easternmost areas (Tacchi of Seui, Ulassai and Tertenia-
Jerzu), 300 m of the Dorgali Dolostones Fm. are overlain abruptly by
little, previously unknown, calcareous outcrops, having a maximum
thickness of 40 m, referable to the M. Tului and M. Bardia Fms
(AMADESI et alii, 1960). These are formed by oolitic calcarenites,
oolitic-bioclastic calcirudites-calcarenites, coralline framestones,
subordinated calcilutites and possible accumulations of fore-reef
breccias. The presence of Ellipsactinia suggests an Upper Jurassic
age. The depositional environments of the Monte Bardia and Monte
Tului Fms. could be referred to platform margin areas where oolitic
bars and limited bioconstructions (patch-reef) developed. Based on
the described data, and taking in account the low protecting bioconstruction
belt, the whole sedimentation environment can be referred
to a shelf with ramp configuration. The overall depositional framework
of the Jurassic succession can be related to a progressively
deepening transgressive sequence, maybe correlatable with the
extensional tectonics causing the development of the Tethys sea.
Finally, an attempt has been made to hypotesize a regional framework
of the Tacchi area both within the Sardinian Mesozoic successions,
and in the Tethyan context
S. Sodi, I cattolici e la vita politica a Pisa durante i pontificati di Leone XIII e Pio X (1878-1914), Pisa 2023
No full textRecensione in rivist
Review on magnonics with engineered spin textures
No full textSpin textures, such as non-uniform domain arrangements, domain walls and skyrmions are naturally occurring structures in magnetic materials. Recently, the unique properties of spin textures such as their reconfigurability, stability and scalability towards nanoscale dimensions, has sparkled the interests towards their use as active elements in spintronic devices. In the framework of magnonics, which aims to use spin waves (SWs) for carrying and processing information, using spin textures allows to harness an extremely rich phenomenology for designing new functionalities. In this review, we focus on the recent developments on the control and stabilization of engineered spin textures, and their applications in the field of magnonics. First, we introduce the main techniques used for stabilizing the spin textures and controlling their properties. Then we review the recent results on the use of engineered spin textures for guiding, emitting and manipulating SWs, and the recent proposals on the realization of complex functionalities using integrated spin-texture-based systems, which hint to possible future directions for technological prospects
Hypopterygium tamarisci (Sw.) Brid. ex Müll. Hal. (Hypopterygiaceae, Bryopsida), new to Italy.
No full textAngular Band Diagrams for Multidirectional Spin Wave Propagation in Square Antidot Lattices
No full textBy means of a joint experimental and theoretical investigation, we propose an alternative way of describing band properties of collective spin waves (SWs) when considering their propagation direction across a magnonic crystal (in our case, a square antidot lattice, ADL): to build up an angular band diagram, in which frequency is plotted as a function of the angle of SW propagation. Similarly to conventional band diagrams, even in this case different dispersions of different modes give origin to allowed/forbidden bands, related not only to the specific in-plane angle at which they are considered, but also to the SW wavevector magnitude and the ADL constant. We performed Brilluoin light scattering (BLS) measurements on a Permalloy ADL (with a lattice constant of 440 nm), mounted on a two-axis goniometer, which allows us to choose a specific angle of incidence of light as well as to rotate the sample around the surface normal (azimuthal rotation). By changing these angles, it is possible to change the magnitude and/or the in-plane direction of the wavevector of light (and, as a consequence, of the detected SW) [1]. In Fig. 1, we show an example of angular band diagram for a SW with k=1.06×2π/a (corresponding to a light incidence angle of 40 degrees): full circles are the experimental data, lines are the dispersions calculated by means of the dynamical matrix method (DMM) [2]. As apparent in Fig. 1, a minimum gap between the most intense SW modes occurs close to φG=28 degrees: however, this value is critically dependent on the wavevector magnitude (and the lattice constant, if different ADLs are compared). We derive and prove this functional dependence with analitical considerations. We believe that this results are of interest for magnon-spintronic applications where a straight antenna on an ADL is used to emit SWs in any direction (omnidirectional SW emission).
References:
[1] G. Gubbiotti, F. Montoncello,S. Tacchi, M. Madami, G. Carlotti, L. Giovannini, J. Ding and A. O. Adeyeye, Applied Physics Letters 106, 262406 (2015).
[2] L. Giovannini, F. Montoncello, and F. Nizzoli, Physical Review B 75, 024416 (2007)
Spin wave band structure of a two-dimensional ferromagnetic antidot array -- Presentazione orale by R. Zivieri - Conferenza internazionale
No full textThe spin wave band structure of a two-dimensional square array of NiFe circular antidots (ADs) has been investigated both experimentally and theoretically by using Brillouin light scattering (BLS) technique and micromagnetic calculations, carried out by means of the dynamical matrix method (DMM) with implemented periodic boundary conditions [1]. Sample consists of 22 nm NiFe film with etched circular having diameter of 120 nm and periodicity of 800 nm. As depicted in the inset to Fig.1, the external magnetic field is applied along y direction, while the transferred wave vector is along x direction. Both the experimental measurements and the calculated spin wave dispersion provide evidence for either extended or localized magnonic modes having a propagative nature. Extended modes spreading in the “horizontal” channels comprised between adjacent rows of ADs have a non-vanishing precession amplitude also along the horizontal rows of holes. These spin-wave modes are labelled as DEnBZ (black curves) where nBZ denotes a given Brillouin zone with n=1,2,.. Instead, the other kind of spin-wave modes, mainly localized along the horizontal rows of antidots, the so-called localized modes [2], are labelled as DElocnBZ (red curves). Both families of modes exhibit bandgaps at Brillouin zone boundaries predicted by the DMM calculations. Opening of bandgaps is interpreted in terms of Bragg diffraction of spin waves from the AD lattice and a quantitative explanation of this effect is given by studying the behavior of the mean internal field. The calculated mean internal field experienced by the two kind of modes is strongly inhomogeneous and is larger in correspondence of ADs. The DE2BZ mode exhibits its maximum precession amplitude where the internal field is larger (smaller) and has thus a larger (smaller) frequency. Band gaps are also calculated within the analytical model according to a perturbation approach. The eigenfunctions representing frequency modes at the BZs boundaries belonging to n-th and (n+1)-th band (sin (k π / a) x and cos (k π / a) x with k = 1,2,.., respectively) are interchanged with respect to those of electrons in electronic bands studied within the nearly-free electron model. This can be understood taking into account that the periodic mean internal field has its maxima in correspondence of ADs, while the periodic electronic potential is minimum close to the nuclei and vice versa. A comparison between the bandgap measured by BLS and the values calculated by means of the analytical model and by using the DMM is shown in Table 1. According to the analytical model, it is found that the relevant scattering potential for Bragg reflection is not provided by the holes themselves, but by the concomitant internal field inhomogeneity between holes [3]. This is in contrast to antidots in photonics and electronics where the back-reflection is directly caused by the presence of holes. The results of this study are important also for the potential applications of these patterned structures that can be used in magnonic devices. Indeed, AD behaves not only as waveguide for spin waves, but the presence of bandgaps permits to filter the frequency of travelling excitations. In this way, AD can be used also as a filter for spin waves.
The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement n228673 (MAGNONICS).
[1] L. Giovannini, F. Montoncello, and F. Nizzoli, Phys. Rev. B 75, 024416 (2007)
[2] S. Tacchi, M. Madami, G. Gubbiotti, G. Carlotti, A.O. Adeyeye, S. Neusser, B. Botters, and D. Grundler,
IEEE Trans. Magn. 46, 172 (2010)
[3] R. Zivieri, S. Tacchi, F. Montoncello, L. Giovannini, F. Nizzoli, M. Madami, G. Gubbiotti, G. Carlotti, S.
Neusser, G. Duerr, and D. Grundler, “Bragg diffraction of spin waves from a two dimensional antidot lattice
”, in press in Physical Review B --
Presentazione orale by R. Zivieri - Conferenza internazional
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