Repulsive Casimir force between Weyl semimetals

Understand

Weyl semimetals are a class of topological materials that exhibit a bulk Hall effect due to time-reversal symmetry breaking.

• We show that for the idealized semi-infinite case, the Casimir force between two identical Weyl semimetals is repulsive at short range and attractive at long range.
• Considering plates of finite thickness, we can reduce the size of the long-range attraction even making it repulsive for all distances when thin enough.
• In the thin-film limit, we study the appearance of an attractive Casimir force at shorter distances due to the longitudinal conductivity.