Ab initio study of magnetite (Fe3O4). The Verwey transition, the Mössbauer spectrum, the half metallic character vs. the semiconducting nature and the role of the symmetry

MEDINA CHANDUVÍ H.H.; A.V. GIL REBAZA; K.L. SALCEDO RODRÍGUEZ; A.M. MUDARRA NAVARRO; J.J. MELO QUINTERO; L.A. ERRICO; C.E. RODRÍGUEZ TORRES

Brasov

Conferencia; International Conference on the Applications of the Mössbauer Effect - ICAME 2021; 2021

ferrites (XFe2O4 ) are a family of magnetic oxides that, due to their numerous technological applications and intriguing magnetic properties, becomes one of the most extensively studied magnetic materials.Ferrites crystallize in the spinel face-centered cubic structure and are characterized by an atomic arrangement of two cationic sites: sites A (tetrahedral oxygen coordination) and sites B (octahedral oxygen coordination). Two types of ferrites can be distinguished; Normal structure: X 2+ ions occupy the A sites and the Fe 3+ ions occupy the B sites Inverted structure: sites are populated by Fe 3+ ions and Fe 3+ and X 2+ ions occupy the B sites in the same proportion. (there are also cases of partial inversion).Iron-ferrite (Fe3O4 , magnetite) is a magnetic material with many technological applications that has been extensively studied for the past half-century, but the charge order below the so-called Verwey transitiontemperature (TV, 120 K) has not been completely understood. Above TV magnetite presents a half metallic behavior. Below TV the conductivity of the system decreases abruptly, and a semiconducting character isreported. This first-order metal-insulator transition is associated with a reduction of the symmetry from the cubic Fd3̅ m structure to a monoclinic Cc structure. The transition has been viewed as an order-disorder transition related to the arrangement of cations on the B sites of the inverse spinel structure.