Jacob Ruff
CHESS, Cornell University
Modern synchrotron x-ray sources enable unparalleled microscopic investigations of materials. By performing x-ray scattering experiments under the application of time-dependent external perturbations, it is possible to define new materials response functions which provide complementary (and often superior) information when compared to their conventional analogs. In this seminar, I will begin by briefly reviewing the recent progress that has been made modernizing the CHESS facility at Cornell, with the construction of the first high-brightness undulator beamlines there. I will then proceed with two examples where probing the time-dependent response of materials with x-rays enables a unique window on the underlying physics, . In the first example, I will show that diffraction measurements of an iron arsenide superconductor under the application of pulsed magnetic fields can reveal the intrinsic “nematic” character of the magnetic susceptibility. In the second example, I will show that diffuse scattering from semiconducting materials under applied thermal gradients can be used to “unpack” the band and momentum dependence of the lattice thermal conductivity. In each case, it will be argued that the information revealed by these custom x-ray experiments would be inaccessible in conventional measurements of magnetic susceptibility or thermal conductivity.
local host: Michel Gingras
