https://doi.org/10.1140/epjb/s10051-021-00213-9
Regular Article – Solid State and Materials
Nematic-like band splitting and crystal field splitting in newly discovered hybrid 12442 iron-based superconductors
1
Human Resources Development Section, Raja Ramanna Centre for Advanced Technology, 452013, Indore, India
2
Homi Bhabha National Institute, BARC Training School Complex, Anushakti Nagar, 400094, Mumbai, India
c hngenator@gmail.com, hng@rrcat.gov.in
Received:
29
July
2021
Accepted:
20
September
2021
Published online:
9
October
2021
We present theoretical results of crystal field splitting and nematic-like band splitting based on density functional theory first principles electronic structure and Wannier fitted tight binding calculations on the newly discovered quasi two-dimensional 
(where A = K, Rb, Cs) i.e., 12442 iron-based superconductors. The orbital selective anisotropy of band structures as well as Fermi surfaces are discussed through electronic structure calculations. The degeneracy of 
and 
orbitals are lifted in 12442 compounds due to the reduction of local symmetry 
to 
of Fe-site. This degeneracy lifting of and cause band reconstruction which in turn induce emergence of nematic-like splitting of some bands in these compounds. This splitting is maximum at the electron bands near the Brillouin zone corner. The details of band reconstruction and band splittings are explored using relativistic pseudopotential including spin orbit coupling. To verify the degeneracy lifting of 
level in 12442 compounds, crystal field splitting is calculated with tight binding fitting using maximally localized Wannier functions. In contrary to its parent 1111 and 122 compounds, the degeneracy lifting of may be responsible for intrinsic band splitting in tetragonal phase of these compounds.
© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2021
