title: Dynamical diffraction theory for wave packet propagation in deformed crystals.
abstract: We develop a theory for the trajectory of an x ray in the presence of a crystal deformation. A set of equations of motion for an x-ray wave packet including the dynamical diffraction is derived, taking into account the Berry phase as a correction to geometrical optics. The trajectory of the wave packet has a shift of the center position due to a crystal deformation. Remarkably, in the vicinity of the Bragg condition, the shift is enhanced by a factor omega/deltaomega (omega: frequency of an x ray, deltaomega: gap frequency induced by the Bragg reflection). Comparison with the conventional dynamical diffraction theory is also made.
authors.affiliation: Department of Applied Physics, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. sawada@appi.t.u-tokyo.ac.jp
authors.forename: Kei
authors.initials: K
authors.lastname: Sawada
authors.forename: Shuichi
authors.initials: S
authors.lastname: Murakami
authors.forename: Naoto
authors.initials: N
authors.lastname: Nagaosa