PT-symmetry in macroscopic magnetic structures

TL;DR

This paper explores PT-symmetry in magnetic nanostructures, demonstrating a phase transition between stable and unstable dynamics in coupled ferromagnetic films with balanced gain and loss.

Contribution

It introduces PT-symmetry in magnetic systems and shows the existence of a spontaneous symmetry-breaking point with distinct dynamical regimes.

Findings

Existence of a PT-symmetry breaking point in magnetic nanostructures

Real eigenfrequencies indicate stable dynamics below the transition

Complex eigenfrequencies indicate unstable dynamics above the transition

Abstract

We introduce the notion of PT-symmetry in magnetic nanostructures and show that they can support a new type of non-Hermitian dynamics. Using the simplest possible set-up consisting of two coupled ferromagnetic films, one with loss and another one with a balanced amount of gain, we demonstrate the existence of a spontaneous PT-symmetry breaking point where both the eigenfrequencies and eigenvectors are degenerate. Below this point the frequency spectrum is real indicating stable dynamics while above this point it is complex signaling unstable dynamics.