  Magnonic black holes-analogue event horizons for the spin-wave collective
excitations of ordered magnets-can be used for fundamental research, for
example for investigating Hawking radiation, but also for technological
applications of spin waves. Here we show how to engineer a horizon for spin
waves in antiferromagnets, which have the attractive feature of fast
magnetization dynamics and linear dispersion relation. We propose a set-up with
spatially varying exchange interaction with spin transfer torque to implement
the horizon and a second set-up for the amplification of spin waves consisting
of an antiferromagnet subject to a spatially varying external magnetic field
that is driven by spin orbit torque. We compute the values of parameters needed
to implement the horizon and to have amplification of spin waves. We develop
the corresponding Klein-Gordon equation and quantify the amplification. Our
work paves the way for investigation of Hawking radiation of spin waves and for
antiferromagnet-based spin-waves amplifiers.
