Higher-Order Topology of the Axion Insulator EuIn_{2}As_{2}.

Based on first-principles calculations and symmetry analysis, we propose that EuIn_{2}As_{2} is a long-awaited axion insulator with antiferromagnetic (AFM) long-range order. Characterized by the parity-based invariant Z_{4}=2, the topological magnetoelectric effect is quantized with θ=π in the bulk,... View More