Hall Effect Sign-inversion and Parallel Hall Effect in Single-constituent 3D Metamaterials

Abstract

A few years ago, Briane and Milton have shown the existence of three-dimensional, isotropic, periodic metamaterials with a Hall coefficient that is negative with respect to that of its constituents using homogenization theory [1]. They also gave an example of such a metamaterial structure. Recently, we simplified their blueprint decisively and numerically demonstrated this sign-inversion which turned out to be controllable by a structure parameter [2].

We extend this work to single-constituent, anisotropic structures exhibiting a Hall voltage which is parallel to an external magnetic field. Furthermore, our numerical analysis reveals that we can combine orthogonal and parallel Hall voltages and achieve full control over the direction of the Hall voltage in the plane perpendicular to the imposed current by adjusting two structure parameters. On the experimental side we fabricate metamaterial Hall bar samples using three-dimensional direct laser writing [3]. Since the obtained polymer structure is electrically non-conducting we coat it with ZnO using atomic layer deposition [4], a deposition technique featuring outstanding conformality and thickness control.