Spin canting induced nonreciprocal Goos-Hänchen shifts.

Recent studies on surface reflection illustrate how light beams can be laterally shifted from the position predicted by geometrical optics, the so called Goos-Hänchen effect. In antiferromagnets this shifts can be controlled with an external magnetic field. We show that a configuration in which spins cant in response to applied magnetic fields enhance possibilities of field controlled shifts. Moreover, we show that nonreciprocal displacements are possible, for both oblique and normal incidence, due to inherent nonreciprocity of the polariton phase with respect to the propagation direction. In the absence of an external field, reciprocal displacements occur.

Using phonon resonances as a route to all-angle negative refraction in the far-infrared region: the case of crystal quartz.

We consider how all-angle negative refraction may be induced in anisotropic crystals by making use of the phonon response. We investigate the example of crystal quartz at far-infrared wavelengths. Reflection and transmission measurements confirm the expected behavior, and show relatively high transmission efficiency at frequencies at which negative refraction occurs.