Electronic Structure and Bonding in Epitaxially Stabilized Cubic Iron Silicides

Дата и время публикации : 1993-05-11T22:54:31Z

Авторы публикации и институты :
K. A. Mader
H. von Kanel
A. Baldereschi

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 15 pages, REVTeX 3.0
Первичная категория: cond-mat

Все категории : cond-mat

Краткий обзор статьи: We present an ab initio full-potential linearized augmented plane-wave (FLAPW) study of the structural and electronic properties of the two bulk unstable compounds FeSi (CsCl structure) and FeSi$_2$ (CaF$_2$ structure) which have recently been grown by molecular beam epitaxy on Si(111). We obtain equilibrium bulk lattice constants of 2.72 AA and 5.32 AA for FeSi and FeSi$_2$, respectively. The density of states (DOS) of FeSi agrees well with experiment, and shows metallic behavior. In agreement with a previous calculation the DOS of FeSi$_2$ shows a large density of $d$-states at the Fermi level, explaining the instability of the bulk phase. The electron charge distributions reveal a small charge transfer from Si to Fe atomic spheres in both compounds. While in FeSi the Fe-Si bond is indeed partially ionic, we show that in FeSi$_2$ the electron distribution corresponds to a covalent charge accumulation in the Fe-Si bond region. The reversed order of $d$-bands in FeSi with respect to FeSi$_2$ is understood in terms of crystal field splitting and Fe-Fe nearest neighbor $dd$-interactions in the CsCl structure, and a strong Si $p$/Fe $d$ bonding in the fluorite structure, respectively.

Category: Physics