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F Parmigiani

Publications and source records attributed to F Parmigiani.

At least 19 recordsLinked to original sources
PubMed2006

Elastic and magnetic dynamics of nanomagnet-ordered arrays impulsively excited by subpicosecond laser pulses.

This Letter reports on the first observation of elastic and magnetic dynamics of ordered arrays of permalloy nanodots excited by low-intensity 120 fs light pulses. The first order of the diffraction pattern, generated by the probe beam in a pump-probe configuration, is used for time-resolved reflectivity and time-resolved magneto-optical Kerr effect measurements. The nonadiabatical absorption of the pump triggers an acoustic standing wave, detected by the reflected probe signal, with a frequency related to the array wave vector. Instead, the magneto-optical signal exhibits, on the nanosecond time scale, the signature of the heat-exchange diffusion processes. In addition, a clear oscillation of the magnetic signal, at a frequency close to the frequency of the acoustic wave, is unambiguously detected. Finally, the interplay between the elastic and magnetic dynamics is analyzed and interpreted.

Journal Article↗
PubMed2005

Direct investigation of orbital ordering in a colossal magnetoresistance manganite by means of X-ray linear dichroism at the Mn L edge.

We have investigated for the first time the orbital ordering in a three-dimensional colossal magnetoresistance manganite, namely La(7/8)Sr(1/8)MnO3, by applying soft X-ray linear dichroism (XLD) to the Mn L edge. We found that the cooperative Jahn-Teller distorted orthorhombic phase, which is present at a temperature of 240 K, is probably accompanied by a predominantly cross type (x2 - z2)/(y2 - z2) orbital ordering. This result is discussed in the light of different exchange interaction models.

Letter↗
PubMed2005

Electronic properties of a pure and sodium-doped C(70) single layer adsorbed on Al polycrystalline surface.

Core level and valence band photoemission measurements combined with near edge x-ray absorption fine structure measurements were performed on a single C(70) layer adsorbed on polycrystalline Al (1 ML-C(70)/Al) (ML-monolayer), pure and doped with sodium atoms. The data obtained from the pure ML chemisorbed on Al surface show a semiconducting behavior of the system, which is characterized by a covalent bond between the adsorbate and the substrate. The same data show also that the C(70) molecules tend to orient themselves with the C(5v) axis perpendicular to the surface in analogy to what observed for 1 ML-C(70)/Cu(111). By doping the sample with sodium atoms a charge transfer from the alkali atoms to the lowest unoccupied molecular orbital (LUMO) of the C(70) molecules takes place, as underlined by the gradual increasing intensity of the C(70) LUMO peak as a function of doping. Nevertheless, no metallic phases are observed for any doping step.

Journal Article↗
PubMed2004

Orientation-dependent C60 electronic structures revealed by photoemission spectroscopy.

We observe, with angle-resolved photoemission, a dramatic change in the electronic structure of two C60 monolayers, deposited, respectively, on Ag (111) and (100) substrates, and similarly doped with potassium to half filling of the C60 lowest unoccupied molecular orbital. The Fermi surface symmetry, the bandwidth, and the curvature of the dispersion at Gamma point are different. Orientations of the C60 molecules on the two substrates are known to be the main structural difference between the two monolayers, and we present new band-structure calculations for some of these orientations. We conclude that orientations play a key role in the electronic structure of fullerides.

Journal Article↗
PubMed2004

Implant-prosthetic rehabilitation after excision of hard palate gland carcinoma.

In Summer 2002, a patient with frequent epistaxis was admitted to the San Gerardo Hospital. Local examination showed a big mass in the nasal fossa. TC and RMN revealed a diffuse erosion of the palatal bone and infiltration of the maxilla. The tumor was removed and histological examination showed a gland carcinoma. The young age of the patient and the need of an adequate bone reconstruction led to use osteoperiosteal calf bone graft. Subsequently, using local anesthesia, 6 implants were positioned. After normal healing and the period of osteointegration, a Toronto bridge was made on implants that the patient wears with no problem.

Adenocarcinoma, Clear Cell↗
PubMed2003

Band structure and Fermi surface of electron-doped C60 monolayers.

C60 fullerides are challenging systems because both the electron-phonon and electron-electron interactions are large on the energy scale of the expected narrow band width. We report angle-resolved photoemission data on the band dispersion for an alkali-doped C60 monolayer and a detailed comparison with theory. Compared to the maximum bare theoretical band width of 170 meV, the observed 100-meV dispersion is within the range of renormalization by electron-phonon coupling. This dispersion is only a fraction of the integrated peak width, revealing the importance of many-body effects. Additionally, measurements on the Fermi surface indicate the robustness of the Luttinger theorem even for materials with strong interactions.

Journal Article↗
PubMed2001

Surface and bulk normal state transport properties in K(3)C(60).

The temperature dependence of the surface resistivity for a metallic K(3)C(60) ordered film in the nonsuperconducting state has been obtained by reflection electron energy loss spectroscopy. We demonstrate that the normal state electronic and transport properties of the top molecular layer of K(3)C(60) are similar to the corresponding properties measured with bulk sensitive techniques. These observations strengthen and give a general character to the experimental results obtained with surface sensitive techniques on fullerene compounds. In addition, the transport properties may deviate from the Fermi-liquid behavior above 500 K.

Journal Article↗
PubMed2000

Atomic many-body effects for the p-shell photoelectron spectra of transition metals.

Ab initio theoretical results for the 2p- and 3p-hole states of an Mn(2+) ion are reported in order to determine the importance of atomic contributions to the photoelectron spectra of bulk MnO. A combined treatment of relativity and electron correlation reveals important physical effects that have been neglected in virtually all previous work. The many-body and relativistic effects included in the atomic model are able, without any ad hoc empirical parameters, to explain most of the features of the MnO photoelectron spectra. In particular, it is not necessary to invoke charge transfer to explain the complex p-level spectra.

Journal Article↗
PubMed1998

[Posterior auricular muscle reflex in the study of the facial muscle function].

To date the study of facial nerve function is based on just two tests: electroneurography (ENGH) and electromyography (EMG). Nevertheless neither of these tests gives reliable results until 8-10 days after onset of the paralysis. The authors have used an evoked auditory potential--more specifically the posterior auricular muscle reflex (PAMr) which is directly activated by the VII cranial nerve in the brainstem after acoustical stimulation. They first tested this method in normal subjects and later in patients with Bell's Palsy and the Ramsey Hunt Syndrome. The authors assert the predictive capacity of this test, in particular, underlining the clear-cut relationship between the time required for the paralysis to heal and the difference in side-to-side PAMr latency. While the sensitivity of the ENGH and PAMr tests are similar, PAMr makes staging of the evolution possible on the 2nd day after onset.

Electromyography↗