1,721,088 research outputs found
Anomalous effect of Li-Al codoping in MgB2: A simple explanation
No full textBy means of first-principles calculations we investigate the possibility that coincorporation of Li and Al in MgB2 could result in an effective "isoelectronic" doping, such as to introduce chemical and structural disorder while leaving unchanged the occupation of the sigma and pi bands. Our results show that the effect on electronic structure of codoping in MgB2 is far from trivial, and shed light on the experimental findings indicating a scarce contribution of Li to the superconducting properties of Mg1-x(AlLi)(x)B-2. The latter result has often been unnecessarily interpreted in terms of the experimental difficulty of actually incorporating Li into the samples
STRUCTURAL, ELECTRONIC AND MAGNETIC-PROPERTIES OF METAL-SEMICONDUCTOR SUPERLATTICES - FE/ZNSE(001)
No full textMETAL-SEMICONDUCTOR INTERFACES - MAGNETIC AND ELECTRONIC-PROPERTIES AND SCHOTTKY-BARRIER IN FEN/(ZNSE)M (001) SUPERLATTICES
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Maximally localized Wannier functions in antiferromagnetic MnO within the FLAPW formalism
No full textFirst-principle investigation of native and impurity defects in MgB2
No full textWe use first-principles techniques to investigate the properties of native defects and impurities in MgB2. We focus our investigation on those defects that could have a relevant role in Al and Li co-doped MgB2. This system shows an anomalous dependence of superconductivity on doping concentration, not yet understood. Structural effects such as segregation and clustering have been put forward to justify experimental evidence. Here we show that native defects have very high formation energies, that Al and Li do not form aggregates and incorporate as substitutional defects randomly distributed on the Mg sublattice sites. There exists a competition between segregation and incorporation of Li, the latter being slightly favored energetically. Our results suggest that anomaly in the superconducting behavior must be accounted for by electronic structure effects
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