Structural and Magnetic Instabilities in LnCd₃P₃ (Ln = La, Ce, Pr, Nd)

Geometrically frustrated lattices have been known to give rise to various unconventional long-range states when populated by spin, orbital, and charge degrees of freedom. In this talk, I will present results on the LnCd₃P₃ (Ln = La, Ce, Pr, Nd) family of materials, which possess layers of Ln³⁺ cations arranged in a triangular-network separated by cadmium phosphide layers that contain a triangular-network of rare trigonal planar Cd²⁺ cations. The former magnetic layers give rise to geometric magnetic frustration, resulting in unconventional magnetic behaviors observed especially in the end member NdCd₃P₃. The trigonal planar CdP₃ units in the latter layers, on the other hand, give rise to bond frustration, and diffuse x-ray scattering data reveal an underlying instability that breaks rotational symmetry in the local structure. I will present results primarily on this structural instability, and, time permitting, present on the unconventional magnetism in NdCd₃P₃. Our results showcase how geometric frustration can give rise to unconventional magnetic and structural instabilities and demonstrate the LnCd₃P₃ family as a materials platform in which these can exist simultaneously, potentially impacting one another.