Consistent model of magnetism in ferropnictides

TitleConsistent model of magnetism in ferropnictides
Publication TypeJournal Article
Year of Publication2011
AuthorsWysocki AL, Belashchenko KD, Antropov VP
Journal TitleNature Physics
Date Published06
Type of ArticleArticle
ISBN Number1745-2473
Accession NumberISI:000291146500017
Keywordsiron, state, superconductivity

The discovery of superconductivity in LaFeAsO introduced ferropnictides as a new class of superconducting compounds with critical temperatures second only to those of the cuprates. Although the presence of iron makes the ferropnictides radically different from the cuprates, antiferromagnetism in the parent compounds suggests that superconductivity and magnetism are interrelated in both of them. However, the character of magnetic interactions and spin fluctuations in ferropnictides is not reasonably described by conventional models of magnetism. Here we show that the most puzzling features can be naturally reconciled within a rather simple effective spin model with a biquadratic interaction, which is consistent with electronic structure calculations. By going beyond the Heisenberg model, our description explains numerous experimental observations, including the peculiarities of the spin-wave spectrum, thin domain walls and crossover from a first- to second-order phase transition under doping. The model also offers insight into the occurrence of the nematic phase above the antiferromagnetic phase transition.

URL<Go to ISI>://000291146500017
Alternate JournalNat. Phys.