Anisotropic Electronic Structure of the Kondo Semiconductor CeFe2Al10 Studied by Optical Conductivity

We report temperature-dependent polarized optical conductivity [$\sigma(\omega)$] spectra of CeFe$_2$Al$_{10}$, which is a reference material for CeRu$_2$Al$_{10}$ and CeOs$_2$Al$_{10}$ with an anomalous magnetic transition at 28 K. The $\sigma(\omega)$ spectrum along the b-axis differs greatly from that in the $ac$-plane, indicating that this material has an anisotropic electronic structure. At low temperatures, in all axes, a shoulder structure due to the optical transition across the hybridization gap between the conduction band and the localized $4f$ states, namely $c$-$f$ hybridization, appears at 55 meV. However, the gap opening temperature and the temperature of appearance of the quasiparticle Drude weight are strongly anisotropic indicating the anisotropic Kondo temperature. The strong anisotropic nature in both electronic structure and Kondo temperature is considered to be relevant the anomalous magnetic phase transition in CeRu$_2$Al$_{10}$ and CeOs$_2$Al$_{10}$.Comment: 5 pages, 4 figure

Models for the magnetic ac susceptibility of granular superferromagnetic CoFe/Al2_2O3_3

The magnetization and magnetic ac susceptibility, $\chi = \chi' - i \chi''$, of superferromagnetic systems are studied by numerical simulations. The Cole-Cole plot, $\chi''$ vs. $\chi'$, is used as a tool for classifying magnetic systems by their dynamical behavior. The simulations of the magnetization hysteresis and the ac susceptibility are performed with two approaches for a driven domain wall in random media. The studies are motivated by recent experimental results on the interacting nanoparticle system Co$_{80}$Fe$_{20}$/Al$_{2}$O$_{3}$ showing superferromagnetic behavior. Its Cole-Cole plot indicates domain wall motion dynamics similarly to a disordered ferromagnet, including pinning and sliding motion. With our models we can successfully reproduce the features found in the experimental Cole-Cole plots.Comment: 8 pages, 6 figure

Glacigenic features and Tertiary stratigraphy of the Magellan Strait (Southern Chile)

The seismostratigraphic and structural analysis of the whole length of the Magellan Strait, from the Atlantic to the Pacific entrance is for first time illustrated on the basis of multichannel seismic (MCS) profiles. The Strait crosses a geologically complex region that includes different morphotectonic provinces, and has been subdivided into three distinct segments, eastern (Atlantic), central, and western (Pacific), being each segment characterized by peculiar sedimentary and tectonic architectures. The MCS profiles shed light on the subsurface of the region in particular on the Quaternary and Tertiary features. In the foreland basin province, the MCS profiles imaged an almost undeformed structural and stratigraphic frame with very thick Cretaceous to Tertiary package. Seismic evidence of deformation of the foreland units occurs in the fold-and-thrust belt province. Along the Cordillera province, the Magallanes-Fagnano transform fault exerts an important morpho-tectonic control that strongly conditions its bathymetric profile. The seismic profiles also highlighted a number of depositional features linked to the up to 150 m thick sedimentary record of the glacial cycles. Whereas the eastern segment (outer foreland province) is devoid of significant glacial-related deposits, the central segment (inner foreland and fold-and thrust belt provinces) shows evidence of repeated advances and retreats of the Magellan glacier. An important moraine ridge complex, probably corresponding to the glacial advance "D"of Clapperton et al., has been seismically imaged in the central segment, as well as an older, large bank of ice distal sediments that have been interpreted as proglacial lake deposits, which show evident signs of repeated glacial erosions. Ice-contact features in the form of frontal moraine complexes made up of dipping foreset strata are present in the fjord-like, western segment of the Strait (Cordillera province), along with their related ice-proximal and ice-distal facies. Eventually, the occurrence of preglacial sediments tectonized by the Magallanes-Fagnano transform fault has been reported in the same segment. This fact, which is supported by small outcrops reported in the updated geologic map, if substantiated by further investigations (i.e. advanced seismic reprocessing, sea bottom samplings), would prove the relatively young age (Late Miocene?) of the Magallanes-Fagnano transform fault

Synchronization in Scale Free networks: The role of finite size effects

Synchronization problems in complex networks are very often studied by researchers due to its many applications to various fields such as neurobiology, e-commerce and completion of tasks. In particular, Scale Free networks with degree distribution $P(k)\sim k^{-\lambda}$, are widely used in research since they are ubiquitous in nature and other real systems. In this paper we focus on the surface relaxation growth model in Scale Free networks with $2.5< \lambda <3$, and study the scaling behavior of the fluctuations, in the steady state, with the system size $N$. We find a novel behavior of the fluctuations characterized by a crossover between two regimes at a value of $N=N^*$ that depends on $\lambda$: a logarithmic regime, found in previous research, and a constant regime. We propose a function that describes this crossover, which is in very good agreement with the simulations. We also find that, for a system size above $N^{*}$, the fluctuations decrease with $\lambda$, which means that the synchronization of the system improves as $\lambda$ increases. We explain this crossover analyzing the role of the network's heterogeneity produced by the system size $N$ and the exponent of the degree distribution.Comment: 9 pages and 5 figures. Accepted in Europhysics Letter