Publication No.38



P. Sánchez, A. Stashans. Computational study of structural and 
electronic properties of superconducting La-doped SrTiO3 
- Phil. Mag. B, 2001, Vol. 81, p. 1963-1976.. 

Abstract:
	Motivated by discovery of the superconductivity in strontium 
titanate (SrTiO3) doped with a small number of electron carriers, we have 
carried out quantum-chemical Hartree-Fock calculations to study La-doped 
SrTiO3. The crystalline lattice distortion due to the impurity presence 
is obtained for both cubic and tetragonal structures. The atomic 
movements in a region surrounding the defects show considerable differences 
for two crystallographic phases.  La-induced local energy levels are 
found in the gap between the upper valence band and the conduction 
band. Two different states of system, namely singlet and triplet, are 
considered. These states occur depending on how the extra electrons fill in 
the local energy levels. The observed electron transfer from the local 
energy levels to the conduction band is discussed in the light of the 
available experimental data on the superconductivity studies.




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