Measurement of the cardiac electrical activity allows following the heart dynamics. Usually measured with electrodes during an electrocardiogram (ECG), this activity can also be studied by monitoring the magnetic component, induced by the circulation of the heart electric currents. This is called "magnetocardiography (MCG).

In a vortex-state magnetic nanodisk, the static magnetization is curling in the plane, except in the disk center where it is pointing out-of-plane, either up (polarity p=+1) or down (p=-1). The lowest energy excitation mode of this ground state is the so-called gyrotropic mode [1], corresponding to a gyration of the vortex core around its equilibrium position at the center of the disk.