Electronic, magnetic and transport properties of Fe intercalated 2H-TaS2_2 studied by means of the KKR-CPA method

The electronic, magnetic and transport properties of Fe intercalated 2H-TaS$_2$ have been investigated by means of the Korringa-Kohn-Rostoker (KKR) method. The non-stoichiometry and disorder in the system has been accounted for using the Coherent Potential Approximation (CPA) alloy theory. A pronounced influence of disorder on the spin magnetic moment has been found for the ferro-magnetically ordered material. The same applies for the spin-orbit induced orbital magnetic moment and magneto-crystalline anisotropy energy. The temperature-dependence of the resistivity of disordered 2H-Fe$_{0.28}$TaS$_2$ investigated on the basis of the Kubo-St\v{r}eda formalism in combination with the alloy analogy model has been found in very satisfying agreement with experimental data. This also holds for the temperature dependent anomalous Hall resistivity $\rho_{\rm xy}(T)$. The role of thermally induced lattice vibrations and spin fluctuations for the transport properties is discussed in detail

Electronic structure and magnetic properties of CrSb2_2 and FeSb2_2 investigated via ab-initio calculations

The electronic structure and magnetic properties of CrSb$_2$ have been investigated by ab-initio calculations with an emphasis on the role of the magnetic structure for the ground state. The influence of correlation effects has been investigated by performing fixed spin moment (FSM) calculations showing their important role for the electronic and magnetic properties. The details of the electronic structure of CrSb$_2$ are analyzed by a comparison with those of FeSb$_2$. The results obtained contribute in particular to the understanding of the temperature dependence of transport and magnetic behavior observed experimentally

Measures of the Soft X-ray Excess as an Eigenvector 1 Parameter for Active Galactic Nuclei

We present a preliminary analysis of X-ray data of quasars in the context of the 4D eigenvector 1 parameter space (Sulentic et al.2000a, b). 4DE1 serves as a surrogate H-R diagram for representing empirical diversity among quasars and identifying the physical drivers of the diversity. The soft X-ray spectral index (Γ) was adopted as one of the key 4DE1 that correlates contrasting extremes in Type 1 properties. 4DE1 motivated the hypothesis of two quasar populations (A and B) divided by L/L≈0.2. Pop. A is a largely radio-quiet population with FWHM Hβ<4000 km/s and often showing a soft X-ray excess. Pop. B is a mix of radio-quiet and a majority of RL quasars shows only a hard X-ray power-law SED. The X-ray separation was based upon earlier ROSAT and ASCA data but we now confirm this dichotomy with large samples of X-ray spectra obtained with XMM-Newton and SWIFT. One popular idea connects the soft excess in Pop. A quasars as a signature of thermal emission from a hot accretion disk in sources radiating close to the Eddington limit.This research was supported by the Spanish Ministry of Economy and Competitiveness through projects AYA2010-15169 and AYA2013-42227-P and by the Junta de Andalucia project TIC 114. KS acknowledges financial support from the Ministerio de Economia y Competitividad through the Spanish grant BES-2014-069767. The authors thank the referee for useful suggestions. This research made use of the NASA IPAC extragalactic database (NED), which is operated by the JPL under contract with the National Aeronautics and Space Administration. This research has made use of the NED database which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We thank the SDSS collaboration for providing the extraordinary database and processing tools that made part of this work possible. The SDSS website is http://www.sdss.org/.Peer reviewe