Who
Benjamin Frandsen (Brigham Young University)
Abstract
The coupling of spin, charge, orbital, and lattice degrees of freedom is of fundamental importance to many functional and quantum materials. This coupling is typically discussed in terms of global symmetries and well-ordered crystallographic phases. However, these global symmetries do not always tell the whole story; increasing evidence suggests that local correlations within a given degree of freedom, e.g. short-range magnetic or structural correlations that average away to zero on longer length scales, can often play a decisive role. In this talk, I will present a sampling of topical materials where short-range correlations carry long-range implications by facilitating the coupling of microscopic degrees of freedom in novel ways, with important consequences for macroscopic material properties. Examples include magnetostructural coupling in the antiferromagnetic semiconductor MnTe, magnetoelectric coupling in the multiferroic perovskite (Sr,Ba)MnO3, and magnetic degeneracy lifting in the triangular lattice antiferromagnet NaMnO2. Along the way, I will introduce magnetic pair distribution function (mPDF) analysis as a powerful tool for probing local magnetic correlations and briefly describe its development over the past ten years. These results highlight the importance of understanding the local structure in complex materials and provide an exciting outlook on the use of mPDF to study short-range correlations as a route to achieving novel functionalities.