Anomalous magnetic properties of Fe_3O_4 nanostructures on GaAs substrate probed using X-ray magnetic circular dichroism

摘要

We have studied the magnetic properties and electronic structure of 2 nm Fe3O4 film on GaAs substrates, which evolve in a nano-tip structure and compared it with 150 nm thick Fe3O4 film. Valence band studies reveal a drop in density of states at Fermi level for 2 nm film as compared to thicker film. XMCD studies divulge the unusual high magnetization value of similar to 5.1 mu(B)/FU in 2 nm film compared to 3.9 mu(B)/FU observed for bulk Fe3O4 or thicker Fe3O4 films. The excess moment is shown to be due to orbital moment contribution.