Julia E. Medvedeva

Electronic structure of superconducting MgB 2 and related binary and ternary borides

First-principles full potential linear muffin-tin orbital--generalized gradient approximation electronic structure calculations of the new medium-T{sub C} superconductor (MTSC) MgB{sub 2} and related diborides indicate that superconductivity in these compounds is related to the existence of p{sub x,y}-band holes at the {Gamma} point. Based on these calculations, we explain the absence of medium-T{sub C} superconductivity for BeB{sub 2}, AlB{sub 2}, ScB{sub 2}, and YB{sub 2}. The simulation of a number of MgB{sub 2}-based ternary systems using a supercell approach demonstrates that (i) the electron doping of MgB{sub 2} (i.e., MgB{sub 2-y}X{sub y} with X=Be, C, N, O) and the creation of defects in the boron sublattice (nonstoichiometric MgB{sub 2-y}) are not favorable for superconductivity, and (ii) a possible way of searching for similar or higher MTSC should be via hole doping of MgB{sub 2} (CaB{sub 2}) or isoelectronic substitution of Mg (i.e., Mg{sub 1-x}M{sub x}B{sub 2} with M=Be, Ca, Li, Na, Cu, Zn) or creating layered superstructures of the MgB{sub 2}/CaB{sub 2} type.

The effect of Coulomb correlation and magnetic ordering on the electronic structure of two hexagonal phases of ferroelectromagnetic YMnO3

The electronic structure of YMnO3 in its high- and low-temperature hexagonal phases has been investigated within the local spin-density approximation (LSDA) and by the LSDA + U method which takes into account the local Coulomb interaction between d electrons of transition-metal ions. In contrast to the case for orthorhombic manganites, the d4-configuration degeneracy is already lifted in the high-temperature symmetric hexagonal phase, indicating that Mn3+ is not a Jahn-Teller ion; hence, we argue that the lowering of the symmetry is not connected with Jahn-Teller instability in hexagonal YMnO3. Each of these two hexagonal phases is found to be semiconducting, with a band gap of about 1.5 eV. It is shown that magnetism and correlation effects are important in band-gap formation for both crystal structures. Using the Green function method, we estimated the Neel temperature from the calculated effective exchange interaction parameters, and found it to be in good agreement with experiment.

Tuning the properties of complex transparent conducting oxides: Role of crystal symmetry, chemical composition, and carrier generation

The electronic properties of single- and multication transparent conducting oxides (TCOs) are investigated using first-principles density-functional approach. A detailed comparison of the electronic band structure of stoichiometric and oxygen deficient

The structure and properties of amorphous indium oxide

{\text{In}}_{2}{\text{O}}_{3}

Combining high conductivity with complete optical transparency: A band structure approach

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Hopping versus bulk conductivity in transparent oxides: 12CaO∙7Al2O3

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Magnetism in bcc and fcc Fe with carbon and manganese

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Averaging of the electron effective mass in multicomponent transparent conducting oxides

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Electronic structure of La0.7Sr0.3Mn1?xCuxO3 (0.0?x?0.30)

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Electronic Structure and Light-Induced Conductivity of a Transparent Refractory Oxide

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