Crystal Lattice Witness vs Actor Roles in Correlated Electronic Materials

Abstract

The line which separates a witness from an actor is very thin, and strongly correlated microscopic mechanisms in complex materials can be either or both at once. In some cases, such as the geometrically-frustrated quantum magnet, Shastry–Sutherland compound SrCu2(BO)3, the crystal lattice appears to stabilize field-induced magnetic superstructures. In others, such as the antiferromagnetic electrically insulating nuclear fuel UO2, or the metallic URu2Si2 the lattice is arguably a silent witness for phase transitions, the symmetry of ordered states, unusual antiferromagnetic domains flip, and standing magneto-elastic waves driven by a still unidentified mechanism. Understanding the roles assumed by different mechanisms when using external tuning parameters such as temperature, magnetic/electric fields, pressure, strain, or others is crucial to success in tuning desired functionality. Here we discuss experimental studies of the crystalline lattice in complex metallic and electrically insulating magnetic materials under extreme conditions of pulsed magnetic fields at cryogenic temperatures. We summarize findings from FBG-based dilatometry studies developed for and completed in static-fields to 45 T, non-destructive pulsed-fields to 100 T, and single-turn destructive pulsed magnetic fields to 150 T.