PT-Symmetric Magnon Lasing and Anti-Lasing

TL;DR

This paper proposes a tunable PT-symmetric magnonic device that can act as both a magnon laser and absorber, enabling reconfigurable magnonic signal processing through current-controlled gain and loss mechanisms.

Contribution

It introduces a novel electrically tunable PT-symmetric magnonic device with a periodic structure that achieves simultaneous lasing and anti-lasing functionalities.

Findings

Demonstrates controllable magnon lasing at the Bragg point.

Shows tunability of lasing and absorption via current density and device parameters.

Validates the concept with analytical and numerical models.

Abstract

A mechanism for electrically tunable PT-symmetric magnonic lasing and anti-lasing is proposed along with a device consisting of a current-biased region in a magnetically ordered planar waveguide. Within the bias area, several heavy-metal wires carrying dc charge current are periodically attached to the waveguide and exert so spatially periodic spin-orbit torques, producing current-controllable modulated magnon gain and loss. It is demonstrated that this decorated waveguide can emit a strong, single frequency magnon mode at the Bragg point (lasing) and also absorb at the same frequency phase-matched incoming coherent magnons (anti-lasing). The underlying physics is captured by an analytical model and validated with full material and device-specific numerical simulations. The magnonic laser absorber response is tunable via the current density in the wires, the extent of the biased region, and the intrinsic damping, enabling the control of lasing frequency and emission power. The structure is shown to amplify thermal magnons, offering a route to low-noise on-chip microwave sources. The concept is compatible with planar waveguides, ring geometries, and antiferromagnets. The results establish an experimentally realistic platform where a single element functions simultaneously as both magnon laser and absorber, opening opportunities for reconfigurable non-Hermitian magnonics and integrated magnon signal processing.