Magnetism and exchange coupling in iron pnictides
|Title||Magnetism and exchange coupling in iron pnictides|
|Publication Type||Journal Article|
|Year of Publication||2010|
|Authors||Pulikkotil JJ, Ke L, van Schilfgaarde M, Kotani T, Antropov VP|
|Journal Title||Superconductor Science & Technology|
Using linear-response density-functional theory, we obtain the magnetic interactions in several iron pnictides. The ground state has been found to be non-collinear in FeSe, with a large continuum of nearly degenerate states lying very close to the magnetic 'striped' structure. The presence of non-collinearity also seems to be a generic feature of iron pnictides when the Fe moment is small. At small RFe-Se the system is itinerant: strong frustration gives rise to an excess of spin entropy, long ranged interactions create incommensurate orderings and strong biquadratic coupling violates the applicability of the Heisenberg model. There is a smooth transition to more localized behavior as RFe-Se increases: stable magnetic orbital order develops which favors long range AFM stripe ordering with strongly anisotropic in-plane exchange couplings. The stabilization of the stripe magnetic order is accompanied by the inversion of the exchange coupling.
|URL||<Go to ISI>://000277029800017|