A Unifying Perspective of Common Motifs That Occur across Disparate Classes of Materials Harboring Displacive Phase Transitions

摘要

Several classes of materials manifest displacive phase transitions, includingshape memory alloys, many electronically correlated materials,superconductors, and ferroelectrics. Each of these classes of materialsdisplays a wide range of fascinating properties and functionalities that arestudied in disparate communities. However, these materials’ classes sharesimilar electronic and phononic instabilities in conjunction withmicrostructural features. Specifically, the common motifs include twinnedmicrostructures, anomalies in the transport behavior, softening of specificphonons, and frequently also (giant) Kohn anomalies, soft phonons, and/ornesting of the Fermi surface. These effects, phenomena, and theirapplications have until now been discussed in separate communities, whichis a missed opportunity. In this perspective a unified framework is presentedto understand these materials, by identifying similarities, defining a unifiedphenomenological description of displacive phase transitions and theassociated order parameters, and introducing the main symmetry-breakingmechanisms. This unified framework aims to bring together experimental andtheoretical know-how and methodologies across disciplines to enableunraveling hitherto missing important mechanistic understanding about thephase transitions in (magnetic) shape memory alloys, superconductors andcorrelated materials, and ferroelectrics. Connecting structural and electronicphenomena and microstructure to functional properties may offer so-farunknown pathways to innovate applications based on these materials.