The Study of Surface Structures by Photoelectron Diffraction and Auger Electron Diffraction

Abstract

ABBREVIA TlONS AND ACRONYMSscanned-energy photoelectron diffraction with normal emission one-dimensional alkali-chain model scanned-energy photoelectron diffraction with off-normal emission photoelectron diffraction path-length difference polar photoelectron diffraction plane-wave scattering Rutherford back scattering surface extended X-ray absorption fine structure strong metal support interaction spin polarized Auger electron diffraction spin polarized photoelectron diffraction short-range magnetic order single scattering single scattering cluster scanning tunneling microscopy spherical-wave scattering X-ray absorption near-edge structure = NEXAFS X-ray photoelectron diffraction, typically at energies of 500-1400 eV X-ray photoelectron spectroscopy

Monte Carlo study of magnetic order at ferromagnetic and antiferromagnetic surfaces: Implications for spin-polarized photoelectron diffraction

“…Spin-polarized photoelectron diffraction (SPPD) has been proposed as a probe for studying short-range magnetic order in both ferromagnetic and antiferromagnetic materials [4][5][6][7][8][9][10]. ln its simplest form, SPPD makes use of multiplet-split core-level binding energies as internally-referenced sources of spin-polarized electrons, with no external spin detector then being necessary.…”

“…ln its simplest form, SPPD makes use of multiplet-split core-level binding energies as internally-referenced sources of spin-polarized electrons, with no external spin detector then being necessary. But if an external spin detector is used with a speciman possessing a net magnetization ( 9) and/or spin-orbit-split levels are excited by circularly-polarized radiation [10], SPPD can be related to an external axis of electron spin polarization. Like the much more developed technique of photoelectron diffraction (PO) without spin resolution [10], SPPD will be primarily sensitive to the first few spheres of neighbors surrounding an emitter [9,10].…”

“…But if an external spin detector is used with a speciman possessing a net magnetization ( 9) and/or spin-orbit-split levels are excited by circularly-polarized radiation [10], SPPD can be related to an external axis of electron spin polarization. Like the much more developed technique of photoelectron diffraction (PO) without spin resolution [10], SPPD will be primarily sensitive to the first few spheres of neighbors surrounding an emitter [9,10]. The fact that SPPD must be carried out at electron kinetic energies of only 50-150 eV in order to have sufficiently strong magnetic scattering also implies high surface sensitivity [9,10], so magnetic properties in the first few layers below a surface are preferentially investigated using this technique.…”

“…Like the much more developed technique of photoelectron diffraction (PO) without spin resolution [10], SPPD will be primarily sensitive to the first few spheres of neighbors surrounding an emitter [9,10]. The fact that SPPD must be carried out at electron kinetic energies of only 50-150 eV in order to have sufficiently strong magnetic scattering also implies high surface sensitivity [9,10], so magnetic properties in the first few layers below a surface are preferentially investigated using this technique. Thus, the change in orientation of magnetic moments in ferromagnetic or antiferromagnetic materials can in principle be studied by analyzing the spin-polarized ~ photoelectron diffraction intensities above a surface as a function of temperature.…”

“…Since SPPD and other probes of surface magnetic order are primarily sensitive to sho.rt-range spin-spin correlations [ 9,10,11,12], the long-range effects in correlation length are not of primary interest here. Also, surface perturbations on underlying layers were found to be negligibly small after about the third layer for the choices of parameter used here.…”