Lateral shift of far infrared radiation on normal incidence reflection off an antiferromagnet

A lateral shift, similar to a Goos-Hänchen shift, of a normally incident electromagnetic beam reflected off an antiferromagnet in the presence of an external magnetic field is predicted. This shift is interpreted in terms of nonreciprocity of the reflected phase, and is confirmed using numerical simulation. There is also a lateral displacement of the field within the antiferromagnet, but not of the beam transmitted through an antiferromagnetic slab.