Superconductivity-induced improper orders in nonsymmorphic systems

Abstract

In this work, we highlight an overlooked mechanism that couples superconducting order parameters to orders in the charge and spin sectors such that the latter emerge as improper orders. At the core of this mechanism are nonsymmorphic symmetries and new families of modulated order parameters with two components of opposite parity. While nonsymmorphic systems have been extensively discussed in the context of topological band theory, our work demonstrates the profound effects of such symmetries on the interplay of ordered phases of matter. As a working example, we focus on the space group P4/nmm and provide a real-space perspective on the classification of order parameters. Our findings can account for the unusual phenomenology of CeRh2As2, a recently discovered heavy fermion superconductor, and open the door for the exploration of nonsymmorphic symmetries in the broader context of improper orders with potential applications to functional topological materials. Published by the American Physical Society 2024