High Temperature Electronic Structure of Fe3O4Fe3O4

Abstract

The high temperature electronic structure and conduction mechanism in Fe3O4Fe3O4 have been investigated through correlations of resistivity and magnetoresistance data with 57Fe NGR. Similar to the resistivity, the relative A and B site isomer shifts are found to decrease rapidly at temperatures well below TN. Above TN the A and B site patterns are unexpectedly poorly resolved and this is found to be due to a reduction in the difference in the electronic structure at the two sites. δB δA is only 0.22 mm s−1 at 855 K compared to the expected value of 0.32 mm s−1 assuming no change in the relative electronic structures at the two sites on passing through the magnetic order disorder transition. No significant changes in the 57Fe NGR parameters are observed at the conductivity maximum near 400 K. These results require a band model for the conduction mechanism above the Verwey transition and non‐negligible conduction electron‐ion core interactions for the A site ions above TN.