Curling spin density and orbital structures in a magnetic vortex core of an Fe quantum dot

First results of the spin and orbital structures in the vortex core of an Fe dot obtained using highly precise first principles calculations that include intra-atomic noncollinear magnetism are reported. We demonstrate that a curling magnetic structure is stabilized within a 4 nm radius dot as inferred from spin-polarized scanning tunneling microscopy experiments in which the spin directions close to the center of the dot turn up along the perpendicular orientation to the curling plane—and also predict a complicated curling intra-atomic noncollinear magnetism near the center in which the spin moments continuously cant in circular directions on a smaller length scale inside the atoms. Importantly, these rotation properties in the spin density couple to the orbital motion and induce orbital moments oriented perpendicular to the curling plane, which is a first prediction of quantum phenomena induced in the nanoscale vortex core.