High magnetic anisotropy of Fe+ ions in KTaO3 and SrCl2

Abstract

The zero-field splitting constant, D, and the gyromagnetic tensor of the off-center systems KTaO3: Fe+ and SrCl2: Fe+ have been explored by means of calculations based on the density-functional theory at the C4v local equilibrium geometry. The calculated D values for KTaO3: Fe + (9 cm-1) and SrCl2: Fe+ (53 cm-1) are found to be much higher than typical figures measured for insulating compounds containing common 3d Kramers ions with a spin S>1/2 in the ground state. This result together with the calculated g and g values concur with available experimental information. The high magnetic anisotropy derived for Fe+ in KTaO3 and SrCl2 is shown to be strongly related to the existence of a E4 excited state lying only at about 3000 and 600 cm -1, respectively, above the ground state. Implications of present findings in the search of new molecular magnets with high values of the magnetic anisotropy are discussed in some detail. © 2010 The American Physical Society.