Macroscopic magnetic structures with balanced gain and loss

We investigate magnetic nanostructures with balanced gain and loss and show that such configurations can result in a new type of dynamics for magnetization. Using the simplest possible setup consisting of two coupled ferromagnetic films, one with loss and another one with a balanced amount of gain, we demonstrate the existence of an exceptional point where both the eigenfrequencies and eigenvectors become degenerate. This point corresponds to a particular value of the gain and loss parameter alpha = alpha(c). For alpha < alpha(c) the frequency spectrum is real, indicating stable dynamics, while for alpha > alpha(c) it is complex, signaling unstable dynamics which is, however, stabilized by nonlinearity.