Néel vector controlled exceptional contours in $p$-wave magnet-ferromagnet junctions

Abstract: Non-Hermitian systems can host exceptional degeneracies where not only the eigenvalues, but also the corresponding eigenvectors coalesce. Recently, $p$-wave magnets have been introduced, which are characterized by their unusual odd parity. In this work, we propose the emergence of non-Hermitian degeneracies at the interface of $p$-wave magnets and ferromagnets. We demonstrate that this setup offers a remarkable tunability allowing realization of exceptional lines and rings, which can be controlled via the orientation of the $p$-wave N\'eel vector. We present the origin of these exceptional contours based on symmetry, and characterize them using phase rigidity. Our works puts forward a versatile platform to realize controllable non-Hermitian degeneracies at odd parity magnetic interfaces.