Competing exchange interactions on the verge of a metal-insulator transition in the two-dimensional spiral magnet Sr3Fe2O7.
Phys Rev Lett
; 113(14): 147206, 2014 Oct 03.
Article
in En
| MEDLINE
| ID: mdl-25325658
ABSTRACT
We report a neutron scattering study of the magnetic order and dynamics of the bilayer perovskite Sr(3)Fe(2)O(7), which exhibits a temperature-driven metal-insulator transition at 340 K. We show that the Fe(4+) moments adopt incommensurate spiral order below T(N) = 115 K and provide a comprehensive description of the corresponding spin-wave excitations. The observed magnetic order and excitation spectra can be well understood in terms of an effective spin Hamiltonian with interactions ranging up to third-nearest-neighbor pairs. The results indicate that the helical magnetism in Sr(3)Fe(2)O(7) results from competition between ferromagnetic double-exchange and antiferromagnetic superexchange interactions whose strengths become comparable near the metal-insulator transition. They thus confirm a decades-old theoretical prediction and provide a firm experimental basis for models of magnetic correlations in strongly correlated metals.
Search on Google
Collection:
01-internacional
Database:
MEDLINE
Type of study:
Prognostic_studies
Language:
En
Journal:
Phys Rev Lett
Year:
2014
Document type:
Article
Affiliation country:
Germany