Extended Data Fig. 1: Electrical anisotropy of existing materials.

The electrical anisotropy of a material is generally determined by its atomic structure. The cubic structure, which is the most isotropic crystal system, is limited to a relatively low electrical anisotropy compared with the high anisotropy of other crystals. The greater the number of elements, the greater the possibility of anisotropy of the atomic structure. Most of the materials with higher electrical anisotropy (for example Bi₂Sr₂Cu₂Ox, MoAlB, V₂AlC, and GaTe) among the existing references contain three or more elements (> ternary). Ag, an elemental material with a cubic structure, exhibits high anisotropy (~27) owing to grain elongation, which suggests that microstructural control and grain orientation are related to the anisotropy of the symmetrical structure. The detailed descriptions of each data point are provided in Supplementary Table 1.