Electronic structure of rare-earth mononitrides: quasiatomic excitations and semiconducting bands

Abstract

The electronic structure of the rare-earth mononitrides LnN (where Ln=rare-earth), which are promising materials for future spintronics applications, is difficult to resolve experimentally due to a strong influence of defects on their transport and optical properties. At the same time, LnN are challenging for theory, since wide semiconducting/semimetallic 2p and 5d bands need to be described simultaneously with strongly correlated 4f states. Here, we calculate the many-body spectral functions and optical gaps of a series of LnN (with Ln= Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er) by a density-functional+dynamical mean-field theory (DFT+DMFT) approach treating the correlated Ln 4f shells within the quasi-atomic Hubbard-I approximation. The on-site Coulomb interaction in the 4f shell is evaluated by a constrained DFT+Hubbard-I approach. Furthermore, to improve the treatment of semiconducting bands in DFT+DMFT, we employ the modified Becke-Johnson semilocal exchange potential. Focusing on the paramagnetic high-temperature phase, we find that all investigated LnN are pd semiconductors with gap values ranging from 1.02 to 2.14 eV along the series. The pd band gap is direct for light Ln= La...Sm and becomes indirect for heavy rare-earths. Despite a pronounced evolution of the Ln 4f states along the series, empty 4f states are invariably found above the bottom of the 5d conduction band. The calculated spectra agree well with those available from x-ray photoemission, x-ray emission and x-ray absorption measurements.

References in corpus (14)

• Dynamical Mean-Field Theory within an Augmented Plane-Wave Framework: Assessing Electronic Correlations in the Iron Pnictide LaFeAsO
• Self-consistency over the charge-density in dynamical mean-field theory: a linear muffin-tin implementation and some physical implications
• Ferromagnetic redshift of the optical gap in GdN
• GW method applied to localized 4f electron systems
• Near-Zero Moment Ferromagnetism in the Semiconductor SmN
• Comparison between experiment and calculated band structures for DyN and SmN
• Spin Density Waves in the Hubbard model - A DMFT approach
• Tuning of Magnetic Activity in Spin-Filter Josephson Junctions Towards Spin-Triplet Transport
• Multiplets Matter: The Electronic Structure of Rare-Earth Semiconductors and Semimetals
• Electronic structure of GdN, and the influence of exact exchange
• Optical Spectroscopy of SmN: Evidence for 4f Transport
• Magnetism and electronic structure calculation of SmN
• 4f Conduction in the Magnetic Semiconductor NdN
• Combining semi-local exchange with dynamical mean-field theory: electronic structure and optical response of rare-earth sesquioxides

Cited by in corpus (6)

• Topological Hall effect induced by chiral fluctuations in ErMn6Sn6
• Tuneable magnetic behaviour, electronic structure and nitrogen vacancy formation in Gd${}_x$Sm${}_{1-x}$N
• Non-collinear magnetism engendered by a hidden another order
• Relation between crystal structure and optical properties in the correlated blue pigment YIn${}_{1-x}$Mn${}_x$O${}_3$
• Weyl nodes and Kondo interaction in noncentrosymmetric semimetals RGaGe (R=La, Ce and Pr) with long Fermi arcs
• Chiral symmetry and magnetism in a 3D Kagome lattice: RPt${}_2$B (R = La and Nd) prototype crystals