Self-induced oscillations in coupled fluxgate magnetometer: a novel approach to operating the magnetic sensors

A fluxgate magnetometer is one of the numerous devices that belong to a class of nonlinear systems known as the overdamped bistable system. Its dynamics can be described by the generic form x=-∇U(x), where U(x) is the potential energy function with two minima that form the bases for the bistability. It is well known that an overdamped system does not oscillate on its own. To switch states, the system is forced by an external periodic signal with large enough amplitude to overcome the potential energy barrier that separates the two minima. However, well-designed coupling schemes, together with the appropriate choice of initial conditions can induce oscillations when a control parameter exceeds a threshold value. The self-induced oscillation, therefore, eliminates the necessity of the forcing function. We demonstrate these concepts numerically and experimentally using three single-domain fluxgate magnetometers that are coupled unidirectionally in a ring.