Effects of pd-hybridization in strongly correlated insulator FeSi

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

“…Since then, FeSi has become an almost iconic system in spin-fluctuation theory of itinerant electron magnetism 13,14 providing the background for testing its various approximations for a long time. 15,16,17,18 The success of spinfluctuation theory in explaining the high temperature susceptibility behavior, inelastic neutron scattering results, and the prediction of the more or less correct band gap value and peaky DOS structure around the Fermi level from band structure calculations have led to the conclusion5 , 14 that band theory provides an adequate description of the physical properties of FeSi, except at elevated temperature where dynamical correlation effects are important for the adequate description of the metal-insulator transitions and temperature delay of the susceptibility growth. 14,19 Indeed modern first-principles based studies of the electronic structure that account for correlation effects within dynamical mean-field theory (LDA+DMFT) 20,21,22 predict simultaneously a closing of the band gap with increasing temperature and describe the temperature of the susceptibility maximum.…”

Numerical simulation of the lattice properties of Fe1–xCoxSi – strongly correlated electron systems

“…The crystal structure of these systems belongs to B20 type with P2 1 3 space group, which is characterized by the absence of inversion center . Such a symmetry causes the emergence of crystallographic chirality, which leads to appearance of the Berry phases and antisymmetric relativistic Dzyaloshinskii–Moriya exchange, which is one of the reasons for the formation of long‐period helical spin spirals with anomalously large magnetic periods (on the order of 100–1000 A), skyrmion phases, and generation of spin current .…”