We report the first direct observation of ferromagnetic spin polarization of Au nanoparticles with a mean diameter of 1.9 nm using x-ray magnetic circular dichroism (XMCD). Owing to the element selectivity of XMCD, only the gold magnetization is explored. Magnetization of gold atoms as estimated by XMCD shows a good agreement with results obtained by conventional magnetometry. This evidences intrinsic spin polarization in nanosized gold.

We clarify the physical origin of anomalies in transverse resistivity often observed in exotic materials, such as SrRuO 3 , in which the Berry curvature is manifested in the transport properties. The previously attributed mechanism for the anomalies, the topological Hall effect (THE) [e.g. Sci. Adv. 2, 160030 (2016)], is refuted by our thorough investigations as well as formulation of a model considering inhomogeneous magnetoelectric properties in the material. Our analyses fully explain every feature of the anomalies without resorting to the THE. The present results establish a fundamental understanding, which was previously overlooked, of magneto-transport properties in such exotic materials.