Role of covalent Fe-As bonding in the magnetic moment formation and exchange mechanisms in iron-pnictide superconductors

TitleRole of covalent Fe-As bonding in the magnetic moment formation and exchange mechanisms in iron-pnictide superconductors
Publication TypeJournal Article
Year of Publication2008
AuthorsBelashchenko KD, Antropov VP
Journal TitlePhysical Review B
Volume78
Pages212505
Date Published12
ISBN Number1098-0121
Accession NumberISI:000262244400019
Keywordsadsorption, antiferromagnetic materials, band structure, bonds (chemical), high-temperature superconductors, iron compounds, lithium compounds, local moments, magnetic anisotropy, superexchange interactions, surface
Abstract

The electronic origin of the huge magnetostructural effect in layered Fe-As compounds is elucidated using LiFeAs as a prototype. The crucial feature of these materials is the strong covalent bonding between Fe and As, which tends to suppress the exchange splitting. The bonding-antibonding splitting is very sensitive to the distance between Fe and As nuclei. We argue that the fragile interplay between bonding and magnetism is universal for this family of compounds. The exchange interaction is analyzed in real space, along with its correlation with covalency and doping. The range of interaction and itinerancy increase as the Fe-As distance is decreased. Superexchange makes a large antiferromagnetic contribution to the nearest-neighbor coupling, which develops large anisotropy when the local moment is not too small. This anisotropy is very sensitive to doping.

URL<Go to ISI>://000262244400019
DOIArtn 212505Doi 10.1103/Physrevb.78.212505