5 research outputs found
Determining the Electron-Phonon Coupling Strength in Correlated Electron Systems from Resonant Inelastic X-ray Scattering
We show that high resolution Resonant Inelastic X-ray Scattering (RIXS)
provides direct, element-specific and momentum-resolved information on the
electron-phonon (e-p) coupling strength. Our theoretical analysis demonstrates
that the e-p coupling can be extracted from RIXS spectra by determining the
differential phonon scattering cross section. An alternative, very direct
manner to extract the coupling is to use the one and two-phonon loss ratio,
which is governed by the e-p coupling strength and the core-hole life-time.
This allows measurement of the e-p coupling on an absolute energy scale.Comment: 4 pages, 3 figure
Resonant Inelastic X-ray Scattering Studies of Elementary Excitations
In the past decade, Resonant Inelastic X-ray Scattering (RIXS) has made
remarkable progress as a spectroscopic technique. This is a direct result of
the availability of high-brilliance synchrotron X-ray radiation sources and of
advanced photon detection instrumentation. The technique's unique capability to
probe elementary excitations in complex materials by measuring their energy-,
momentum-, and polarization-dependence has brought RIXS to the forefront of
experimental photon science. We review both the experimental and theoretical
RIXS investigations of the past decade, focusing on those determining the
low-energy charge, spin, orbital and lattice excitations of solids. We present
the fundamentals of RIXS as an experimental method and then review the
theoretical state of affairs, its recent developments and discuss the different
(approximate) methods to compute the dynamical RIXS response. The last decade's
body of experimental RIXS data and its interpretation is surveyed, with an
emphasis on RIXS studies of correlated electron systems, especially transition
metal compounds. Finally, we discuss the promise that RIXS holds for the near
future, particularly in view of the advent of x-ray laser photon sources.Comment: Review, 67 pages, 44 figure
Spin-Orbital Separation in the quasi 1D Mott-insulator Sr2CuO3
As an elementary particle the electron carries spin \hbar/2 and charge e.
When binding to the atomic nucleus it also acquires an angular momentum quantum
number corresponding to the quantized atomic orbital it occupies (e.g., s, p or
d). Even if electrons in solids form bands and delocalize from the nuclei, in
Mott insulators they retain their three fundamental quantum numbers: spin,
charge and orbital[1]. The hallmark of one-dimensional (1D) physics is a
breaking up of the elementary electron into its separate degrees of freedom[2].
The separation of the electron into independent quasi-particles that carry
either spin (spinons) or charge (holons) was first observed fifteen years
ago[3]. Using Resonant Inelastic X-ray Scattering on the 1D Mott-insulator
Sr2CuO3 we now observe also the orbital degree of freedom separating. We
resolve an orbiton liberating itself from spinons and propagating through the
lattice as a distinct quasi-particle with a substantial dispersion of ~0.2 eV.Comment: 35 pages, 8 figure
King Kold Karnival - Tau Kappa Epsilon, 1979
A member of the Tau Kappa Epsilon Fraternity uses a shovel to prepare a snow sculpture for the 1979 King Kold Karnival. The winter festival known as the King Kold Karnival was a staple at UND from 1951-1968. The event usually included contests, sled races, dances, beauty pageants, and most notably large snow sculptures. A brief resurgence emerged in 1979 but was not continued.https://commons.und.edu/archive-photos/1436/thumbnail.jp