Electronic structure studies of FeSi: A chiral topological system

Emergence of spin-orbit coupled ferromagnetic surface state derived from Zak phase in a nonmagnetic insulator FeSi

“…One motive argument is about surface conduction in a Kondo insulator SmB 6 ( 13 ), which is attributed to the metallic surface state protected by spin-orbit coupling (SOC)–assisted band inversion between 4 f and 5 d orbitals ( 14 ); thus, SmB 6 is proposed to be a topological Kondo insulator ( 15 ). Another incentive is about Fermi-arc surface states observed in compounds with the FeSi-type crystal structure ( 16 , 17 ). The Fermi arcs arise to connect the surface projections of band-crossing points protected by the chiral crystalline symmetry ( 18 , 19 ).…”

Electronic structure and unconventional non-linear response in double Weyl semimetal SrSi$_2$

“…We note that higher topological charge is also observed for multifold band crossing with integer spin in topological chiral crystals such as, the transition metal monosilicides MSi (M = Co, Mn, Fe, Rh) [26][27][28][29][30]. The Fermi arc surface states and chiral anomaly induced negative magnetoresistance directly reflect the topological nature of WSM through its transport signatures [31,32].…”

Electronic correlations effect on nontrivial topological fermions in CoSi

“…For example, spin-1 fermion with 3-fold degeneracy carrying ±2 topological charge, spin-3/2 Rarita-Schwinger-Weyl fermion (RSW) with 4-fold degeneracy carrying ±4 topological charge [28][29][30], double Weyl fermions with ±2 topological charge [31][32][33] and double spin-1 fermion with 6-fold degeneracy [22]. Interestingly, these newly found fermions are predicted to be seen in topological chiral systems like transition-metal (TM) monosilicides such as XSi(X=Co,Rh,Fe) [30,32,[34][35][36][37][38]. Among these the present work is mainly focused onto CoSi for the study.…”