Pair emission from a relativistic domain wall in antiferromagnets

TL;DR

This paper theoretically investigates magnon pair emission from a relativistic domain wall in antiferromagnets, revealing dominant quadratic magnon coupling and enhanced emission near the effective light velocity, with implications for magnon damping.

Contribution

It introduces a theoretical model for magnon pair emission from relativistic domain walls, highlighting the role of quadratic coupling and the influence of wall profile and velocity.

Findings

Pair emission is dominated by quadratic magnon coupling.

Emission rate increases near the effective light velocity.

Ohmic damping due to magnon excitation is calculated.

Abstract

Magnon emission and excitation by a relativistic domain wall at a constant velocity in antiferromagnet is theoretically studied. A pair emission due to a quadratic magnon coupling is shown to be dominant. The emission corresponds in the comoving frame to a vacuum polarization induced by a zero-energy instability of the Lorentz-boosted anomalous response function. The emission rate is sensitive to the magnon dispersion and wall profile, and is significantly enhanced for a thin wall with velocity close to the effective light velocity. The Ohmic damping constant due to magnon excitation at low velocity is calculated.