Branton J. Campbell
ProfessorDepartment of Physics & Astronomy
Brigham Young University
Provo, UT 84602, USA
Tel: 801-422-5758, Fax: 801-422-0553
I apply state-of-the-art x-ray and neutron scattering techniques to study local and long-range structures in a variety of complex solids, including fast-ion conductors, ferroelectric relaxors, high-temperature superconductors, and colossal magnetoresistive manganites, where nanoscale structural features influence macroscopic physical properties. This includes the development of symmetry-mode analysis as a tool for the determination, refinement and interpretation of distorted structures involving lattice strains, atomic displacements, magnetic moments and occupational orderings at both commensurate and incommensurate wavevectors.
Transient Defects Caught in the Act
The anisotropic x-ray diffuse scattering pattern surrounding this Bragg reflection from La1.8Sr2.2Mn2O7 at 125 K provides evidence that Jahn-Teller polarons (football-shaped lattice distortions that follow hopping electrons from site to site) play a role in this material's exotic phase transition from paramagnetic insulator to ferromagnetic metal. This data was used to perform a quantitative three-dimensional structural analysis of transient polaronic distortions.