Measuring the Magnetization from the Image of the Stripe Magnetic Domain

Abstract

Magnetic imaging techniques visualize magnetization states in detail, including magnetization directions and magnetic domains. Generally, such imaging methods determine only the relative magnetization, while the absolute value of magnetization remains unknown. Measuring absolute magnetization requires the separate measurement of a reference material, but for samples with just a few ferromagnetic layers, these techniques can no longer be applied. We show a simple magneto-optical imaging method for obtaining the absolute value of magnetization using the parallel stripe domains formed by an electric current in thin films. The parallel stripes in the films consist of repeating up- and down-magnetized domains with a certain periodicity. In the absence of an external magnetic field, the normalized areas of up and down domains are equal. However, application of an external perpendicular magnetic field can change these normalized areas of each domain because the magnetic field prefers only one domain depending on the direction. Measuring these normalized areas and the stripe periodicity using conventional imaging techniques is sufficient to determine the absolute value of magnetization.