Electronic structures and magnetization reversal in Li0.5FeCr1.5O4

By employing temperature (T)-dependent soft x-ray magnetic circular dichroism (XMCD) in the Fe and Cr 2p absorption edges, the electronic structures of Li0.5FeCr1.5O4 spinel ferrite, which exhibits magnetization compensation, have been investigated. This work provides evidence that (i) both Fe and Cr ions are trivalent, (ii) most of Fe3+ ions occupy the A (T-d) sites, while Cr3+ ions occupy the B (Oh) sites, (iii) the magnetic moments of Fe and Cr ions are coupled antiferromagnetically, and (iv) they are reversed at similar to 255 K. The sum-rule analysis of Fe and Cr 2p XMCD spectra reveals that the orbital magnetic moments of Fe and Cr ions in Li0.5FeCr1.5O4 are much larger than those of metallic Fe and Cr, implying the large spin-orbit coupling and the non-fully occupied t(2g) orbitals of Fe3+ and Cr3+ ions. Based on these findings, we have provided a comprehensive model for the electronic and spin configurations of Fe and Cr ions in (Fe)A[Li0.5Cr1.5]BO4. Published under license by AIP Publishing.