Correlated excited states in the narrow band gap semiconductor FeSi and antiferromagnetic screening of local spin moments

Autor(en)

Sergii Khmelevskyi, Georg Kresse, Peter Mohn

Abstrakt

The physical properties of the semiconductor FeSi with very narrow band gap, anomalous behavior of the magnetic susceptibility and metal-insulator transition at elevated temperatures attract great interest due to the still controversial theoretical understanding of their origin. On one side the purely bandlike mechanism of the gap formation in FeSi at low temperature is well established; on the other side a number of experiments and their theoretical interpretation suggest a rich physics of strong correlations at finite temperature. In this work we use an ab initio scheme based on the random-phase approximation and local spin-density approximation (RPA@LSDA) to reveal the role of the electron correlation effects in FeSi extending it by applying a fixed spin moment constraint. In the parameter-free framework we show that correlation effects essentially alter the one-electron LSDA results leading to the formation of an additional state with finite magnetic moment on Fe, whose energy is almost degenerate with the nonmagnetic ground state. This explains the results of high-field experiments, which found a first-order metamagnetic phase transition into a metallic ferromagnetic state. Our results suggest a strongly correlated nature of the low-energy excitations in FeSi. From our supercells calculations we reveal that these excitations are local and exhibit a Kondo-like behavior since a strong antiferromagnetic screening is present.

Organisation(en)

Computergestützte Materialphysik

Externe Organisation(en)

Technische Universität Wien

Journal

Physical Review B

Band

98

Anzahl der Seiten

8

ISSN

2469-9950

DOI

https://doi.org/10.1103/PhysRevB.98.125205

Publikationsdatum

09-2018

Peer-reviewed

Ja

ÖFOS 2012

103015 Kondensierte Materie, 103011 Halbleiterphysik

Schlagwörter

ASJC Scopus Sachgebiete

Electronic, Optical and Magnetic Materials, Condensed Matter Physics

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/3db12bf2-0d25-4c08-a4d2-dd6ebff302c4