Metamaterials modify the properties of light — bending and shaping it to yield media with exotic capabilities. The earliest metamaterials were designed many decades ago, but so far most have been tailored to modify electromagnetic radiation or sound. Now, Alex Weström and Teemu Ojanen have reapplied this concept to the movement of electrons through conducting crystals.
Instead of changing the permeability and permittivity of the crystal, Weström and Ojanen theoretically proposed that introducing carefully configured perturbations would warp the background against which the electrons move. This is akin to the curving of spacetime by massive objects that produce a gravitational field. If designed correctly, a three-dimensional lens could bend the path of the electrons to periodically focus them at a series of distant points.
Candidate materials include Weyl semimetals, which host relativistic electrons. The warping could be induced by strain, magnetic dopants or layer-by-layer material design. The idea could even be extended to 'cloak' regions of the crystal, rendering them invisible to electrical current. More fundamentally, condensed-matter analogues of phenomena such as black holes could now be within reach.
About this article
Cite this article
Abergel, D. Weyl metamaterials. Nature Phys 13, 1147 (2017). https://doi.org/10.1038/nphys4333