57 research outputs found
Electronic structure, magnetic ordering and X-ray magnetic circular dichroism in LaPrCoP phosphides
The electronic structure and magnetic ordering in LaPrCoP
(0, 0.25, and 1) phosphides have been studied theoretically using the fully
relativistic spin-polarized Dirac linear muffin-tin orbital (LMTO)
band-structure method. The X-ray absorption and X-ray magnetic circular
dichroism spectra at the Co and Pr edges have been
investigated theoretically within the framework of the LSDA+ method. The
core-hole effect in the final state as well as the effects of the electric
quadrupole and magnetic dipole transitions have been investigated.
Good agreement with experimental measurements has been found.Comment: 11 pages, 8 figure
Variation of magnetic properties of SrFeMoO due to oxygen vacancies
Oxygen vacancies can be of utmost importance for improving or deteriorating
physical properties of oxide materials. Here, we studied from first-principles
the electronic and magnetic properties of oxygen vacancies in the double
perovskite SrFeMoO (SFMO). We show that oxygen vacancies can increase
the Curie temperature in SFMO, although the total magnetic moment is reduced at
the same time. We found also that the experimentally observed valence change of
the Fe ions from to in the x-ray magnetic circular dichroism (XMCD)
measurements is better explained by oxygen vacancies than by the assumed mixed
valence state. The agreement of the calculated x-ray absorption spectra and
XMCD results with experimental data is considerably improved by inclusion of
oxygen vacancies.Comment: submitted to PRB but rejected, major revision, submitting to JPC
Saigas on the brink: Multidisciplinary analysis of the factors influencing mass mortality events
In 2015, more than 200,000 saiga antelopes died in 3 weeks in central Kazakhstan. The proximate cause of death is confirmed as hemorrhagic septicemia caused by the bacterium Pasteurella multocida type B, based on multiple strands of evidence. Statistical modeling suggests that there was unusually high relative humidity and temperature in the days leading up to the mortality event; temperature and humidity anomalies were also observed in two previous similar events in the same region. The modeled influence of environmental covariates is consistent with known drivers of hemorrhagic septicemia. Given the saiga population’s vulnerability to mass mortality and the likely exacerbation of climate-related and environmental stressors in the future, management of risks to population viability such as poaching and viral livestock disease is urgently needed, as well as robust ongoing veterinary surveillance. A multidisciplinary approach is needed to research mass mortality events under rapid environmental change
Electronic structure and x-ray magnetic circular dichroism in the Mn₃CuN perovskite
The electronic and magnetic structures of Mn₃CuN are investigated theoretically from first principles using the fully relativistic Dirac LMTO band structure method. Mn₃CuN possesses a magnetic phase transition at TC = 143 K from a high temperature paramagnetic phase to a low temperature ferromagnetic one with a noncollinear magnetic structure. The transition is accompanied by a structural change from the cubic to the tetragonal lattice. In low temperature phase two Cu moments and two Mn moments (Mn₂ and Mn₃) ferromagnetically align along the c axis while other four Mn1 magnetic moments are canted from the c axis to [111] direction by angle Q= ±76.2. The x-ray absorption spectra and x-ray magnetic circular dichroism (XMCD) spectra of Mn₃CuN are investigated theoretically from first principles. The origin of the XMCD spectra in the Mn₃CuN compound is examined. The calculated results are compared with the experimental data
Electronic structure of fully epitaxial Co2TiSn thin films
In this article we report on the properties of thin films of the full Heusler
compound Co2TiSn prepared by DC magnetron co-sputtering. Fully epitaxial,
stoichiometric films were obtained by deposition on MgO (001) substrates at
substrate temperatures above 600{\deg}C. The films are well ordered in the L21
structure, and the Curie temperature exceeds slightly the bulk value. They show
a significant, isotropic magnetoresistance and the resistivity becomes strongly
anomalous in the paramagnetic state. The films are weakly ferrimagnetic, with
nearly 1 \mu_B on the Co atoms, and a small antiparallel Ti moment, in
agreement with theoretical expectations. From comparison of x-ray absorption
spectra on the Co L3/L2 edges, including circular and linear magnetic
dichroism, with ab initio calculations of the x-ray absorption and circular
dichroism spectra we infer that the electronic structure of Co2TiSn has
essentially non-localized character. Spectral features that have not been
explained in detail before, are explained here in terms of the final state band
structure.Comment: 11 pages, 8 figure
Electronic structure and x-ray magnetic circular dichroism in (Ge,Mn)Te diluted magnetic semiconductors
The electronic structure of the (Ge,Mn)Te diluted magnetic semiconductors was investigated theoretically from first principles, using the fully relativistic Dirac linear muffin-tin orbital (LMTO) band structure method. The electronic structure is obtained with the local spin-density approximation (LSDA) as well as the LSDA+U method. The x-ray magnetic circular dichroism (XMCD) spectra of (Ge,Mn)Te DMSs at the Mn L2,3 edges are investigated theoretically from first principles. The origin of the XMCD spectra in the compound is examined. The calculated results are compared with available experimental data
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