Enhanced orbital magnetic moment in FeCo nanogranules observed by Barnett effect

The gyroscopic g factor, g ′ , of FeCo nanogranules embedded in a matrix of MgF 2 (FeCo-MgF 2 ) was determined by measuring the magnetic-field generation from a rotating sample due to the Barnett effect. The g ′ value of the FeCo-MgF 2 is estimated to be 1.76 ± 0.11. The orbital contribution to the magnetic moment in the FeCo nanogranules was found to be quite large compared with that in bulk FeCo, being consistent with a density-functional-theory calculation that shows that the orbital magnetic moment may increase at the FeCo/MgF 2 interfaces. The result suggests that the orbital magnetic moment is enhanced by symmetry breaking at the surface of the FeCo nanogranules.