Quantitative 3D magnetic vector field imaging and thermal sensing with magneto-optical indicator films

Abstract

Magneto-optical indicator films are an established tool for magnetic field imaging in applications such as electronics and superconductors, as well as in magnetic characterization. However, the implementation of combined measurements of temperature and different magnetic field components has been limited. We present a magneto-optical method for the quantitative imaging of three-dimensional magnetic vector fields, using yttrium iron garnet indicator films with in-plane and out-of-plane magnetic anisotropy. For the out-of-plane anisotropy sensor, an additional magneto-optical measurement of temperature is implemented to ensure stability against temperature variations for the three-dimensional magnetic field quantification. In all cases, a tailored sequence of magnetic bias fields is applied to bring the indicator film into a single-domain state along four distinct directions. Alterations in the magnetic field give rise to variations in the coherent rotation of magnetization between the discrete states. By imaging the out-of-plane component of magnetization at each state via magneto-optical microscopy, the local magnetic vector field and temperature are reconstructed. As an example, the magnetic vector field distribution generated by the current of an integrated circuit is measured and compared with the calculated magnetic field distribution. The technique provides magnetic vector field imaging with micrometer spatial resolution, millisecond exposure times, and sub-0.1 mT magnetic field accuracy, making it suitable for the characterization of electronic systems and functional materials in an environment with varying temperatures.