Three-dimensional chiral Veselago lensing

The effect by which light focuses upon entering a medium with a negative refractive index, known as Veselago lensing, may enable optical imaging below the diffraction limit. Similarly, focusing electrons across a p -n junction could realize a technologically promising electronic Veselago lens. However, its scope remains limited by the lack of three-dimensional platforms and its insensitivity to computational degrees of freedom, such as spin or chirality. Here, we propose a single-material three-dimensional electronic Veselago lens that selectively focuses electrons of a given chirality. Using the chiral anomaly of topological semimetals it is possible to create a sharp p -n junction for a single chirality, a chiral Veselago lens, and tune it with a magnetic field to an ideal lensing condition. We estimate that chiral Veselago lensing is observable in nonlocal transport and spectroscopy experiments. In particular, we show that the chiral Veselago lens leads to giant nonlocal magnetoresistance.