B. R. K. Nanda

Electronic structure and magnetism in half-Heusler compounds

In this paper we have applied the full-potential linearized muffin tin orbital method and the tight-binding linearized muffin tin orbital method to investigate in detail the electronic structure and magnetism of a series of half-Heusler compounds XMZ with X = Fe,Co,Ni, M = Ti,V,Nb,Zr,Cr,Mo,Mn and Z = Sb,Sn. Our detailed analysis of the electronic structure using various indicators of chemical bonding suggests that covalent hybridization of the higher-valent transition element X with the lower-valent transition element M is the key interaction responsible for the formation of the d–d gap in these systems. However, the presence of the sp-valent element is crucial to provide stability to these systems. The influence of the relative ordering of the atoms in the unit cell on the d–d gap is also investigated. We have also studied in detail some of these systems with more than 18 valence electrons which exhibit novel magnetic properties, namely half-metallic ferro- and ferrimagnetism. We show that the d–d gap in the paramagnetic state, the relatively large X–Sb hybridization and the large exchange splitting of the M atoms are responsible for the half-metallic property of some of these systems.

Electronic structure of the substitutional vacancy in graphene: density-functional and Green's function studies

We study the electronic structure of graphene with a single substitutional vacancy using a combination of the density-functional, tight-binding and impurity Greens function approaches. Density-functional studies are performed with the all-electron spin-polarized linear augmented plane wave (LAPW) method. The three sp2? dangling bonds adjacent to the vacancy introduce localized states (V?) in the mid-gap region, which split due to the crystal field and a Jahn?Teller distortion, while the pz? states introduce a sharp resonance state (V?) in the band structure. For a planar structure, symmetry strictly forbids hybridization between the ? and the ? states, so that these bands are clearly identifiable in the calculated band structure. As to the magnetic moment of the vacancy, the Hunds rule coupling aligns the spins of the four localized V?1??, V?2? and V?? electrons, resulting in an S?=?1 state, with a magnetic moment of 2?B, which is reduced by about 0.3?B due to the anti-ferromagnetic spin polarization of the ? band itinerant states in the vicinity of the vacancy. This results in the net magnetic moment of 1.7?B. Using the Lippmann?Schwinger equation, we reproduce the well-known ?1/r decay of the localized V? wave function with distance, and in addition, find an interference term coming from the two Dirac points, previously unnoticed in the literature. The long-range nature of the V? wave function is a unique feature of the graphene vacancy and we suggest that this may be one of the reasons for the widely varying relaxed structures and magnetic moments reported from the supercell band calculations in the literature.

Electronic and magnetic structure of the (LaMnO3)2n/(SrMnO3)n superlattices

We study the magnetic structure of the

Effects of strain on orbital ordering and magnetism at perovskite oxide interfaces: LaMnO3/SrMnO3

{({\text{LaMnO}}_{3})}_{2n}/{({\text{SrMnO}}_{3})}_{n}

Strain and electric field modulation of the electronic structure of bilayer graphene

superlattices from density-functional calculations. In agreement with the experiments, we find that the magnetism changes with the layer thickness

Spin-polarized two-dimensional electron gas at oxide interfaces.

n

Electronic structure and magnetism in doped semiconducting half-Heusler compounds

. The reason for the different magnetic structures is shown to be the varying potential barrier across the interface, which controls the leakage of the

Polar catastrophe, electron leakage, and magnetic ordering at the LaMnO3/SrMnO3 interface

\text{Mn-}{e}_{g}

Magnetic and Orbital Order in LaMnO3 under Uniaxial Strain: A Model Study

electrons from the

Electronic structure of half-metallic magnets

{\text{LaMnO}}_{3}