Spin and orbital magnetic moment of reconstructed2×2R45∘magnetite(001)

Abstract

The surface of a magnetite single crystal with (001) orientation has been prepared by sputtering/annealing cycles providing the √ 2 × √ 2R45• reconstruction. The distribution of magnetic domains on the surface has been imaged by x-ray magnetic dichroism in a photoemission microscope. The easy axes are along the surface in-plane 110 directions. The near-surface magnetic moment was determined by applying the sum rules to XMCD spectra obtained with different kinetic energies of the secondary electrons. A reduced total moment of 3.3 μ B and a ratio of about 0.10 between orbital and spin moment was found, which we attribute to the surface reconstruction.

Spin reorientation transition of magnetite (001)

“…As already reported 18 , both the in-plane easy axis directions and the curved domain walls likely originate from the competition of the magnetocrystalline anisotropy and the shape anisotropy on the magnetite (001) near surface region: the observed surface easy-axes correspond to the projection of the bulk ones onto the surface plane. We have observed similar patterns in several samples, both synthetic and natural crystals with different stoichiometries 18,30 and at widely differing cleaning stages, so we believe they are an intrinsic feature of the Fe 3 O 4 (001) surface. We remark that this style of domains are very different from domains experimentally observed in magnetite thin films with (001) orientation [32][33][34][35] .…”

“…Only when the crystal surface has been cleaned by several cycles of sputtering and annealing so it shows the √ 2 × √ 2R45 •27 reconstruction, magnetic contrast is observed. The current model of the reconstructed surface, the subsurface cation vacancy model 29 , makes specific predictions on the magnetic moment of the near surface regions, predictions that have been corroborated by x-ray magnetic circular dichroism 30 . In the present experiments, we focus instead on the distribution of magnetic domains.…”

Memory effect and magnetocrystalline anisotropy impact on the surface magnetic domains of magnetite(001)

“…In particular in the upper part, this extended region shows yellow bands with a periodicity of one micron which corresponds to a zig-zag in-plane canting of up to 30°. We have observed such domain patterns, previously reported by PEEM 10 , on different magnetite crystals, both synthetic 19 and natural 17 , 20 .…”

Geometrically defined spin structures in ultrathin Fe3O4with bulk like magnetic properties

“…S3 †), slightly reduced from the one expected for bulk magnetite as often measured on magnetite surfaces and films depending on the particular state of the surface. 26 In order to obtain the spatially resolved magnetization vector from this and other islands, three consecutive XMCD images are acquired at different azimuthal angles of the sample relative to the X-ray beam. From these, correcting for distortions and transforming from the skew reference axis of the three X-ray incoming directions, a vector map proportional to the local magnetization can be obtained.…”