Debye-Waller effects in Bethe-Salpeter calculations: Bridging the gap between XANES and EXAFS.

We present a method to incorporate Debye-Waller effects on core-excitation spectra within frameworks other than real-space, multiple-scattering formulations. The method draws ideas used in multiple-scattering theory to realize effects of variations in interatomic distances, and the method accomplishes this without benefit of the atom-by-atom nature in which multiple-scattering calculations are formulated. We test the method in four metals and one semiconductor over a range of temperatures and compare all theoretical results to experiment.

Partial densities of states from x-ray absorption and Auger electron spectroscopy: Use of core-hole memory.

Ag edge x-ray absorption and - Auger electron spectra have been measured and simulated for a variety of x-ray electric-field polarization and Auger electron emission directions. The theory relies on density-functional theory, use of the Bethe-Salpeter equation, atomic multiplet theory, and a simplified model for the Auger line shape and its dependence on photon energy. We also demonstrate that partial densities of states for , , and symmetry partial-wave channels at the Ag site in the solid can be deduced from the experimental measurements with only atomic theoretical input, i.

Revisiting the K-edge X-ray absorption fine structure of Si, Ge-Si alloys, and the isoelectronic series: CuBr, ZnSe, GaAs, and Ge.

Extended X-ray absorption fine structure (EXAFS) has evolved into an unprecedented local-structure technique that is routinely used to study materials' problems in the biological, chemical, and physical sciences. Like many other experimental techniques, EXAFS also requires that several key atomic parameters must be known before structural information can be quantitatively determined. Utilizing current analytical methods, we revisit the isoelectronic series CuBr, ZnSe, GaAs, and Ge originally studied by Stern during the early development of EXAFS [E.

Dielectric Relaxation, Local Structure and Lattice Dynamics in Mn-Doped Potassium Tantalate Ceramics.

Alkaline niobate and tantalate perovskites have attracted attention as polar dielectrics for electronics and telecommunications. Here, we studied the polar behaviour, lattice dynamics, and local structure in conventionally processed KMnTaO ceramics using a combination of variable-temperature dielectric and Raman spectroscopies, and X-ray absorption fine structure (XAFS) measurements, respectively. Mn doping induces a low-frequency dielectric relaxation in KTaO (KT), which follows the Arrhenius law with an activation energy ≈ 105 meV and the characteristic relaxation time ≈ 4.

Determination of Hafnium Zirconium Oxide Interfacial Band Alignments Using Internal Photoemission Spectroscopy and X-ray Photoelectron Spectroscopy.

Doped ferroelectric HfO is highly promising for integration into complementary metal-oxide semiconductor (CMOS) technology for devices such as ferroelectric nonvolatile memory and low-power field-effect transistors (FETs). We report the direct measurement of the energy barriers between various metal electrodes (Pt, Au, Ta, TaN, Ti/Pt, Ni, Al) and hafnium zirconium oxide (HfZrO, HZO) using internal photoemission (IPE) spectroscopy. Results are compared with valence band offsets determined using the three-sample X-ray photoelectron spectroscopy (XPS) as well as the two-sample hard X-ray photoelectron spectroscopy (HAXPES) techniques.