Computational study of spin transitions in BaLiF3 containingparamagnetic impurities

Abstract

The aim of this work is the computational study of the electronic andmagnetic properties of [FeO4]5- clusters diluted in a cubichost crystal: BaLiF3. Experimental results show that these systemsdisplay a bistable magnetic behaviour (intermediate spin S = 3/2-high spinS = 5/2 transition), which can be reversibly controlled by temperature orlight illumination. Our calculations, using density functional theory forboth molecular and crystalline models, on two different [FeO4]5- structures, one with D4h symmetry andanother one with C2v symmetry, lead to results that are ingood qualitative agreement with experimental results: the structure withD4h symmetry has a quartet ground state and the structurewith C2v symmetry has a sextet ground state. The observedspin transition may be understood as a consequence of oxygen jumpings intoneighbouring fluorine vacancies in the BaLiF3 matrix under lightor thermal excitation, which would allow transformation from one [FeO4]5- configuration into the other.