Hard X-ray photoelectron spectroscopy from 5–14.5keV

Thieß, S.; Kunz, C.; Cowie, Bruce C. C.; Lee, T.-L.; Renier, M.; Zegenhagen, J.

doi:10.1016/j.ssc.2004.09.021

Cited by 55 publications

(34 citation statements)

References 10 publications

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“…It should be noted that matrix element effects are rendering the photo cross section not only strongly dependent on energy but also on the specific shape of the electron wavefunction. This was for instance demonstrated by Thiess et al [23] as shown in Figure 4. Thus, by choice of excitation energy, the emission from certain electronic levels can be enhanced or suppressed.…”

Section: Hard X-ray Photoelectron Spectroscopysupporting

confidence: 57%

Photoelectron spectroscopy of transition metal oxide interfaces

Zegenhagen

2015

Eur. Phys. J. Appl. Phys.

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Abstract. In the present paper we review applications of the photoelectron spectroscopy (PES) technique to the investigation of transition metal oxide (TMO) interfaces. We summarize very briefly some of the principle, specific characteristics of TMOs. Because of the buried nature of the interfaces, the photoelectrons must penetrate certain thicknesses of material, which is easier with higher kinetic energies in the keV range. Thus, we also briefly summarize some of the hallmarks of hard X-ray photoelectron spectroscopy (HAXPES), before presenting four explicit samples of the analysis of TMO interfaces: The LaAlO 3/SrTiO3(0 0 1) interface, which had attracted attention because of the discovery of a sheet of high mobility electrons below the thin layer of LaAlO3; superlattices of the two insulators CaCuO2 and SrTiO3, which can be prepared to become superconducting at about 40 K; epitaxial films of the 90 K superconductor GdBa2Cu3O 7−δ on NdGaO3; and finally the analysis of the nucleation of the 90 K superconductor YBa2Cu3O 7−δ on SrTiO3(0 0 1). The latter two cases of the investigation of the superconducting films are examples of photoelectron spectroscopy by X-ray standing wave (XSW) excitation. Because of this, the bare essential features of the XSW technique are also briefly reviewed.

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Section: Hard X-ray Photoelectron Spectroscopysupporting

confidence: 57%

Photoelectron spectroscopy of transition metal oxide interfaces

Zegenhagen

2015

Eur. Phys. J. Appl. Phys.

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“…Nowadays, high energy excitation and analysis of the electrons become easily feasible due to the development of high intense sources (insertion devices at synchrotron facilities) and multi-channel electron detection. Thus, high resolution-hard x-ray photo emission spectroscopy (HAXPES) was recently introduced by several groups [79][80][81][82][83][84] as a bulk sensitive probe of the electronic structure in complex materials. Balke et al [37] used HAXPES at hν ≈ 8 keV to study the DOS of Co 2 Mn 1−x Fe x Si with x = 0, 1/2, 1.…”

Section: Methodsmentioning

confidence: 99%

Rational design of new materials for spintronics: Co₂FeZ (Z=Al, Ga, Si, Ge)

Balke

Wurmehl

Fecher

et al. 2008

Science and Technology of Advanced Materials

162

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Spintronic is a multidisciplinary field and a new research area. New materials must be found for satisfying the different types of demands. The search for stable half-metallic ferromagnets and ferromagnetic semiconductors with Curie temperatures higher than room temperature is still a challenge for solid state scientists. A general understanding of how structures are related to properties is a necessary prerequisite for material design. Computational simulations are an important tool for a rational design of new materials. The new developments in this new field are reported from the point of view of material scientists. The development of magnetic Heusler compounds specifically designed as material for spintronic applications has made tremendous progress in the very recent past. Heusler compounds can be made as half-metals, showing a high spin polarization of the conduction electrons of up to 100% in magnetic tunnel junctions. High Curie temperatures were found in Co 2 -based Heusler compounds with values up to 1120 K in Co 2 FeSi. The latest results at the time of writing are a tunnelling magnet resistance (TMR) device made from the Co 2 FeAl 0.5 Si 0.5 Heusler compound and working at room temperature with a (TMR) effect higher than 200%. Good interfaces and a well-ordered compound are the precondition to realize the predicted half-metallic properties. The series Co 2 FeAl 1−x Si x is found to exhibit half-metallic ferromagnetism over a broad range, and it is shown that electron doping stabilizes the gap in the minority states for x = 0.5. This might be a reason for the exceptional temperature behaviour of Co 2 FeAl 0.5 Si 0.5 TMR devices.Using x-ray diffraction (XRD), it was shown conclusively that Co 2 FeAl crystallizes in the B2 structure whereas Co 2 FeSi crystallizes in the L2 1 structure. For the compounds Co 2 FeGa or Co 2 FeGe, with Curie temperatures expected higher than 1000 K, the standard XRD technique using laboratory sources cannot be used to easily distinguish between the two structures. For this reason, the EXAFS technique was used to elucidate the structure of these two compounds. Analysis of the data indicated that both compounds crystallize in the L2 1 structure which makes these two compounds suitable new candidates as materials in magnetic tunnel junctions.

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“…In previous papers [13,14] we have reported measurements of sub-shell cross-sections of gold in the energy range 5-14.5 keV. Particularly interesting are shallow core levels, since the crosssections in the solid may differ from the values for the free atom.…”

Section: Introductionmentioning

confidence: 99%

Relative electron inelastic mean free paths for diamond and graphite at 8keV and intrinsic contributions to the energy-loss

Kunz¹,

Cowie

Drube

et al. 2009

Journal of Electron Spectroscopy and Related Phenomena

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a b s t r a c tWe used hard X-ray photoelectron spectroscopy (HAXPES) with 8 keV X-rays to investigate the 1s emission of carbon. We recorded spectra extending from the peak of the C 1s electrons ("elastic" line) to electrons with up to 110 eV energy-loss. Using two samples side by side, we could compare the inelastic mean free paths (IMFPs) of the electrons of almost 8 keV in diamond and graphite and find them to be practically identical despite about 50% difference in densities. Published extrapolations of their IMFP calculations at lower energies are in good agreement with this result. We show that information from the almost structureless region of overlapping multiple extrinsic energy-losses can be used to quantify the fraction of photoelectrons experiencing intrinsic energy-losses (those due to the sudden creation of the hole). We find that this fraction is 58% of the primary excited C 1s electrons for diamond and is practically the same for graphite. This is at first sight an unexpected result since hole-screening should differ in a semimetal from that in an insulator. The observation can be accounted for by dynamic screening in contrast to static screening.

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Hard X-ray photoelectron spectroscopy from 5–14.5keV

Cited by 55 publications

References 10 publications

Photoelectron spectroscopy of transition metal oxide interfaces

Photoelectron spectroscopy of transition metal oxide interfaces

Rational design of new materials for spintronics: Co₂FeZ (Z=Al, Ga, Si, Ge)

Relative electron inelastic mean free paths for diamond and graphite at 8keV and intrinsic contributions to the energy-loss

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Hard X-ray photoelectron spectroscopy from 5–14.5keV

Cited by 55 publications

References 10 publications

Photoelectron spectroscopy of transition metal oxide interfaces

Photoelectron spectroscopy of transition metal oxide interfaces

Rational design of new materials for spintronics: Co2FeZ (Z=Al, Ga, Si, Ge)

Relative electron inelastic mean free paths for diamond and graphite at 8keV and intrinsic contributions to the energy-loss

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Rational design of new materials for spintronics: Co₂FeZ (Z=Al, Ga, Si, Ge)