The small-bandgap semiconductors LnCd 3 P 3 (Ln = La, Ce, Pr and Nd) are promising materials to study emergent phenomena from geometric frustration across bond, spin and charge degrees of freedom.

A central goal of topological photonics has been to develop compact isolators using protected, non-reciprocal edge states. A recent demonstration of a ferrite-based microwave isolator leverages the ...