138 research outputs found
Localized Magnetic States of Fe, Co, and Ni Impurities on Alkali Metal Films
X-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism
(XMCD) have been used to study transition metal impurities on K and Na films.
The multiplet structure of the XAS spectra indicates that Fe, Co, and Ni have
localized atomic ground states with predominantly d7, d8, and d9 character,
respectively. XMCD shows that the localized impurity states possess large,
atomiclike, magnetic orbital moments that are progressively quenched as
clusters are formed. Ni impurities on Na films are found to be nonmagnetic,
with a strongly increased d10 character of the impurity state. The results show
that the high magnetic moments of transition metals in alkali hosts originate
from electron localization
Design of a tuned vbration absorber (TVA) for applications in transport engineering
The control of the response to tonal excitations or to broadband stochastic disturbances of a stiffened cylinder is investigated through the use of a Tuned Vibrating Absorber (TVA). In particular, the study
considered both a purely passive device (Mechanical) and a semi-active one with shunt circuit (Electro-Mechanical) to evaluate the efficiencies and differences
Correlated Electrons Step-by-Step: Itinerant-to-Localized Transition of Fe Impurities in Free-Electron Metal Hosts
High-resolution photoemission spectroscopy and realistic ab-initio
calculations have been employed to analyze the onset and progression of d-sp
hybridization in Fe impurities deposited on alkali metal films. The interplay
between delocalization, mediated by the free-electron environment, and Coulomb
interaction among d-electrons gives rise to complex electronic configurations.
The multiplet structure of a single Fe atom evolves and gradually dissolves
into a quasiparticle peak near the Fermi level with increasing the host
electron density. The effective multi-orbital impurity problem within the exact
diagonalization scheme describes the whole range of hybridizations.Comment: 10 pages, 4 figure
Development and Applications of a Virtual Hybrid Platform for Multiscale Analysis of Advanced Structures of Aircraft (DEVISU)
This paper outlines the main findings of the project “DEvelopment and applications of a VIrtual hybrid platform for multiscale analysis of advanced StructUres of aircraft” (DEVISU), which deals with failure of composite structures and noise/vibration reduction, along with investigation of new materials for aerospace applications
Ordered vacancy network induced by the growth of epitaxial graphene on Pt(111)
We have studied large areas of (v3×v3)R30° graphene commensurate with a Pt(111) substrate. A combination of experimental techniques with ab initio density functional theory indicates that this structure is related to a reconstruction at the Pt surface, consisting of an ordered vacancy network formed in the outermost Pt layer and a graphene layer covalently bound to the Pt substrate. The formation of this reconstruction is enhanced if low temperatures and polycyclic aromatic hydrocarbons are used as molecular precursors for epitaxial growth of the graphene layers
Equivalent loads for two-dimensional distributed anisotropic piezoelectric transducers with arbitrary shapes attached to thin plate structures
Earthquake nucleation in the lower crust by local stress amplification
Deep intracontinental earthquakes are poorly understood, despite their potential to cause significant destruction. Although lower crustal strength is currently a topic of debate, dry lower continental crust may be strong under high-grade conditions. Such strength could enable earthquake slip at high differential stress within a predominantly viscous regime, but requires further documentation in nature. Here, we analyse geological observations of seismic structures in exhumed lower crustal rocks. A granulite facies shear zone network dissects an anorthosite intrusion in Lofoten, northern Norway, and separates relatively undeformed, microcracked blocks of anorthosite. In these blocks, pristine pseudotachylytes decorate fault sets that link adjacent or intersecting shear zones. These fossil seismogenic faults are rarely >15 m in length, yet record single-event displacements of tens of centimetres, a slip/length ratio that implies >1 GPa stress drops. These pseudotachylytes represent direct identification of earthquake nucleation as a transient consequence of ongoing, localised aseismic creep
A simple method for choosing the parameters of a two degree-of-freedom tuned vibration absorber
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