Publications (2)5.01 Total impact
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Article: Microscopic environment of Fe in epitaxially stabilized c-FeSi
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ABSTRACT: Epitaxially stabilized iron monosilicide films having the CsCl structure (c-FeSi) have been investigated by conversion electron Mössbauer spectroscopy and transmission electron microscopy. The 57Fe Mössbauer parameters (isomer shift δ, linewidth Γ, and quadrupole splitting Δ) are reported and discussed in terms of the local surrounding of the Fe nucleus. High statistical accuracy and resolution allowed a detailed investigation of the effects of strain and of the structural phase transformation from the epitaxially stabilized to the bulk stable phase. The phase transformation was found to proceed in a rather surprising layer by layer mechanism with smooth interfaces between the epitaxially stabilized, the bulk stable, and a third phase. Results from a molecular-dynamics simulation at constant pressure and temperature of the structural phase transition are presented and compared with the experimental findings. The isomer shift and the electric-field gradient at the Fe nucleus in the strained c-FeSi and in the third phase have been calculated using the ab initio full potential linear muffin-tin orbital method. The Mössbauer parameters of some relevant point defects in c-FeSi have likewise been calculated within this framework.Physical Review B 01/1999; 59(5):3675-3687. · 3.69 Impact Factor -
Article: Electronic Structures of Semiconductors under Pressure
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ABSTRACT: The dielectric constants of semiconductors under pressure are derived from ab initio calculations of the complex dielectric functions ε(ω). The pressure coefficient of the refractive index is negative for most tetrahedrally bonded compounds and trends are explained within a simple model. Gap deformation potentials as well as “absolute” band edge deformation potentials are derived, and the pressure dependence of the electronic structure of superlattices is discussed. Examples from the group III-V, in particular nitrides, and II-VI (ZnS, ZnS/ZnSe) compounds illustrate these investigations. Also, less conventional semiconductors, β-FeSi2 and ε-FeSi, are examined. Strong electron correlation effects limit the validity of LDA theory in these cases. It is suggested that experimental pressure studies can shed new light on the properties of Kondo insulators.physica status solidi (b) 10/1996; 198(1):23 - 34. · 1.32 Impact Factor
