Imaging out-of-plane magnetization via the tip-contact-induced anomalous Nernst effect

Budai, N.*; Isshiki, Hironari; Otani, Yoshichika

We present a magnetic imaging technique to investigate materials with perpendicular magnetic anisotropy, using a conventional atomic force microscope (AFM). In this method, the Si tip acts as a thermal anchor, generating localized in-plane temperature gradients in a heated nanowire. The resulting anomalous Nernst effect (ANE) is measured at both ends of the wire. For uniform out-of-plane magnetization, the anomalous Nernst signal reverses the sign as the tip scans from edge to edge, reflecting the direction of the local temperature gradient. By simulating this gradient, the coefficient of the ANE can be quantitatively determined. Furthermore, this technique enables the visualization of magnetic multi-domain structures. This method offers a simple, quantitative, and practical approach to magnetic imaging using widely available AFM setups.