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Magnuson, M., Olovsson, W., Ghafoor, N., Odén, M. & Hultman, L. (2020). Interface bonding of Zr1−xAlxN nanocomposites investigated by x-ray spectroscopies and first principles calculations [Review]. Physical Review Research, 2(1)
Open this publication in new window or tab >>Interface bonding of Zr1−xAlxN nanocomposites investigated by x-ray spectroscopies and first principles calculations
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2020 (English)In: Physical Review Research, E-ISSN 2643-1564, Vol. 2, no 1Article, book review (Refereed) Published
Abstract [en]

The electronic structure, chemical bonding, and interface component in ZrN-AlN nanocomposites formed byphase separation during thin film deposition of metastable Zr1−xAlxN (x = 0.0, 0.12, 0.26, 0.40) are investigatedby resonant inelastic x-ray scattering, x-ray emission, and x-ray absorption spectroscopy and compared to firstprinciples calculations including transitions between orbital angular momentum final states. The experimentalspectra are compared with different interface-slab model systems using first principles all-electron full-potentialcalculations where the core states are treated fully relativistically. As shown in this work, the bulk sensitivity andelement selectivity of x-ray spectroscopy enables one to probe the symmetry and orbital directions at interfacesbetween cubic and hexagonal crystals. We show how the electronic structure develops from local octahedralbond symmetry of cubic ZrN that distorts for increasing Al content into more complex bonding. This results inthree different kinds of bonding originating from semicoherent interfaces with segregated ZrN and lamellar AlNnanocrystalline precipitates. An increasing chemical shift and charge transfer between the elements takes placewith increasing Al content and affects the bond strength and increases resistivity.

Place, publisher, year, edition, pages
College Park, MD, United States: American Physical Society, 2020
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-164339 (URN)10.1103/PhysRevResearch.2.013328 (DOI)
Note

Fulltext published under the terms of the Creative Commons Attribution 4.0 International license. https://creativecommons.org/licenses/by/4.0/

No changes have been made to the fulltext.

Funded by Bibsam.

Available from: 2020-03-18 Created: 2020-03-18 Last updated: 2020-03-23Bibliographically approved
Magnuson, M. & Mattesini, M. (2020). Magnetic anisotropy in Cr2GeC investigated by X-ray magnetic circular dichroism and ab initio calculations. Journal of Magnetism and Magnetic Materials, 501, Article ID 166470.
Open this publication in new window or tab >>Magnetic anisotropy in Cr2GeC investigated by X-ray magnetic circular dichroism and ab initio calculations
2020 (English)In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 501, article id 166470Article in journal (Refereed) Published
Abstract [en]

The magnetism in the inherently nanolaminated ternary MAX-phase Cr2GeC is investigated by element-selective, polarization and temperature-dependent, soft X-ray absorption spectroscopy and X-ray magnetic circular dichroism. The measurements indicate an antiferro-magnetic Cr-Cr coupling along the c-axis of the hexagonal structure modulated by a ferromagnetic ordering in the nanolaminated ab-basal planes. The weak chromium magnetic moments are an order of magnitude stronger in the nanolaminated planes than along the vertical axis. Theoretically, a small but notable, non-spin-collinear component explains the existence of a non-perfect spin compensation along the c-axis. As shown in this work, this spin distortion generates an overall residual spin moment inside the unit cell resembling that of a ferri-magnet. Due to the different competing magnetic interactions, electron correlations and temperature effects both need to be considered to achieve a correct theoretical description of the Cr2GeC magnetic properties.

Place, publisher, year, edition, pages
Elsevier, 2020
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-163499 (URN)10.1016/j.jmmm.2020.166470 (DOI)000513901000033 ()
Note

Funding agencies: Swedish Research CouncilSwedish Research Council; Linnaeus Grant LiLi-NFM; Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research; Swedish Energy Research [43606-1]; Carl Tryggers Foundation [CTS16:303, CTS14:310]; Spanis

Available from: 2020-02-06 Created: 2020-02-06 Last updated: 2020-03-09Bibliographically approved
Magnuson, M., Tengdelius, L., Greczynski, G., Eriksson, F., Jensen, J., Lu, J., . . . Högberg, H. (2019). Compositional dependence of epitaxial Tin+1SiCn MAX-phase thin films grown from a Ti3SiC2 compound target. Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, 37(2), Article ID 021506.
Open this publication in new window or tab >>Compositional dependence of epitaxial Tin+1SiCn MAX-phase thin films grown from a Ti3SiC2 compound target
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2019 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 37, no 2, article id 021506Article in journal (Refereed) Published
Abstract [en]

The authors investigate sputtering of a Ti3SiC2 compound target at temperatures ranging from RT (no applied external heating) to 970 °C as well as the influence of the sputtering power at 850 °C for the deposition of Ti3SiC2 films on Al2O3(0001) substrates. Elemental composition obtained from time-of-flight energy elastic recoil detection analysis shows an excess of carbon in all films, which is explained by differences in the angular distribution between C, Si, and Ti, where C scatters the least during sputtering. The oxygen content is 2.6 at. % in the film deposited at RT and decreases with increasing deposition temperature, showing that higher temperatures favor high purity films. Chemical bonding analysis by x-ray photoelectron spectroscopy shows C–Ti and Si–C bonding in the Ti3SiC2 films and Si–Si bonding in the Ti3SiC2 compound target. X-ray diffraction reveals that the phases Ti3SiC2, Ti4SiC3, and Ti7Si2C5 can be deposited from a Ti3SiC2 compound target at substrate temperatures above 850 °C and with the growth of TiC and the Nowotny phase Ti5Si3Cx at lower temperatures. High-resolution scanning transmission electron microscopy shows epitaxial growth of Ti3SiC2, Ti4SiC3, and Ti7Si2C5 on TiC at 970 °C. Four-point probe resistivity measurements give values in the range ∼120 to ∼450 μΩ cm and with the lowest values obtained for films containing Ti3SiC2, Ti4SiC3, and Ti7Si2C5.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2019
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-154004 (URN)10.1116/1.5065468 (DOI)000460437200051 ()
Note

Funding agencies: Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Swedish Energy Research [43606-1]; Carl Tryggers Foundation [CTS16:303, CTS14:310, CTS 17:166]; Knut 

Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-03-20Bibliographically approved
Magnuson, M., Greczynski, G., Eriksson, F., Hultman, L. & Högberg, H. (2019). Electronic Structure of ß-Ta Films from X-ray Photoelectron Spectroscopy and First-principles Calculations. Applied Surface Science, 470, 607-612
Open this publication in new window or tab >>Electronic Structure of ß-Ta Films from X-ray Photoelectron Spectroscopy and First-principles Calculations
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2019 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 470, p. 607-612Article in journal (Refereed) Published
Abstract [en]

The electronic structure and chemical bonding of ß-Ta synthesized as a thin 001-oriented film (space group P 21m) is investigated by 4f core level and valence band X-ray photoelectron spectroscopy and compared to α-Ta bulk. For the b-phase, the 4f7/2 peak is located at 21.91 eV and with the 4f5/2 at 23.81 eV which is 0.16 eV higher compared to the corresponding 4f peaks of the a-Ta reference. We suggest that this chemical shift originates from higher resistivity and tensile strain in the ß-Ta film. Furthermore, the 5d-5s states at the bottom of the valence band are shifted by 0.75 eV towards higher binding energy in ß-Ta compared to α-Ta. This is a consequence of the lower number of nearest neighbors with four in ß-Ta compared to eight in the α-Ta phase. The difference in the electronic structures, spectral line shapes of the valence band and the energy positions of the Ta 4f, 5p core-levels of b-Ta versus a-Ta are discussed in relation to calculated states of ß-Ta and α-Ta. In particular, the lower number of states at the Fermi level of ß-Ta (0.557 states/eV/atom) versus α-Ta (1.032 states/eV/atom) that according to Mott’s law should decrease the conductivity in metals and affect the stability by charge redistribution in the valence band. This is experimentally supported from resistivity measurements of the film yielding a value of ~170 µW cm in comparison to α-Ta bulk with a reported value of ~13.1 µW cm.

Keywords
β-Ta films, Valence band measurements, First-principles calculations, X-ray photoelectron spectroscopy, High power impulse magnetron sputtering
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-152876 (URN)10.1016/j.apsusc.2018.11.096 (DOI)000454997100069 ()
Note

Funding agencies: Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linkoping University [2009-00971]; Swedish Energy Research [43606-1]; Carl Tryggers Foundation [CTS16:303, CTS14:310, CTS 17:166]; Knut and Alice Wallenber

Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2019-01-21
Magnuson, M., Tengdelius, L., Eriksson, F., Samuelsson, M., Broitman, E., Greczynski, G., . . . Högberg, H. (2019). Reactive magnetron sputtering of tungsten target in krypton/trimethylboron atmosphere. Thin Solid Films, 688, Article ID 137384.
Open this publication in new window or tab >>Reactive magnetron sputtering of tungsten target in krypton/trimethylboron atmosphere
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2019 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 688, article id 137384Article in journal (Refereed) Published
Abstract [en]

W-B-C films were deposited on Si(100) substrates held at elevated temperature by reactive sputtering from a W target in Kr/trimethylboron (TMB) plasmas. Quantitative analysis by Xray photoelectron spectroscopy (XPS) shows that the films are W-rich between ~ 73 and ~ 93 at.% W. The highest metal content is detected in the film deposited with 1 sccm TMB. The C and B concentrations increase with increasing TMB flow to a maximum of ~18 and ~7 at.%, respectively, while the O content remains nearly constant at 2-3 at.%. Chemical bonding structure analysis performed after samples sputter-cleaning reveals C-W and B-W bonding and no detectable W-O bonds. During film growth with 5 sccm TMB and 500 o C or with 10 sccm TMB and 300-600 o C thin film X-ray diffraction shows the formation of cubic 100-oriented WC1-x with a possible solid solution of B. Lower flows and lower growth temperatures favor growth of W and W2C, respectively. Depositions at 700 and 800 o C result in the formation of WSi2 due to a reaction with the substrate. At 900 o C, XPS analysis shows ~96 at.% Si in the film due to Si interdiffusion. Scanning electron microscopy images reveal a fine-grained microstructure for the deposited WC1-x films. Nanoindentation gives hardness values in the range from ~23 to ~31 GPa and reduced elastic moduli between ~220 and 280 GPa in the films deposited at temperatures lower than 600 o C. At higher growth temperatures the hardness decreases by a factor of 3 to 4 following the formation of WSi2 at 700-800 o C and Si-rich surface at 900 o C.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
W-B-C films, reactive magnetron sputtering, trimethylboron, nanoindentation, Xray photoelectron spectroscopy, thin film X-ray diffraction, Scanning Electron Microscope
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-160243 (URN)10.1016/j.tsf.2019.06.034 (DOI)000485256500039 ()2-s2.0-85067891667 (Scopus ID)
Available from: 2019-09-13 Created: 2019-09-13 Last updated: 2019-11-14Bibliographically approved
Olovsson, W., Mizoguchi, T., Magnuson, M., Kontur, S., Hellman, O., Tanaka, I. & Draxl, C. (2019). Vibrational Effects in X-ray Absorption Spectra of Two-Dimensional Layered Materials. The Journal of Physical Chemistry C, 123(15), 9688-9692
Open this publication in new window or tab >>Vibrational Effects in X-ray Absorption Spectra of Two-Dimensional Layered Materials
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2019 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 15, p. 9688-9692Article in journal (Refereed) Published
Abstract [en]

With the examples of the C K-edge in graphite and the B K-edge in hexagonal boron nitride, we demonstrate the impact of vibrational coupling and lattice distortions on the X-ray absorption near-edge structure (XANES) in two-dimensional layered materials. Theoretical XANES spectra are obtained by solving the Bethe–Salpeter equation of many-body perturbation theory, including excitonic effects through the correlated motion of the core hole and excited electron. We show that accounting for zero-point motion is important for the interpretation and understanding of the measured X-ray absorption fine structure in both materials, in particular for describing the σ*-peak structure.

Place, publisher, year, edition, pages
ACS Publications, 2019
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-156490 (URN)10.1021/acs.jpcc.9b00179 (DOI)000465488600005 ()
Note

Funding agencies:  Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; Knut and Alice Wallenbergs Foundation; Swedish Energy Research [43606-1]; Carl Trygger Foundation [CTS16:303, CTS14:310]; JSPS KA

Available from: 2019-04-24 Created: 2019-04-24 Last updated: 2020-03-19Bibliographically approved
Magnuson, M., Halim, J. & Näslund, L.-Å. (2018). Chemical bonding in carbide MXene nanosheets. Journal of Electron Spectroscopy and Related Phenomena, 224, 27-32
Open this publication in new window or tab >>Chemical bonding in carbide MXene nanosheets
2018 (English)In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 224, p. 27-32Article in journal (Refereed) Published
Abstract [en]

tThe chemical bonding in the carbide core and the surface chemistry in a new group of transition-metalcarbides Tin+1Cn-Tx(n = 1,2) called MXenes have been investigated by surface-sensitive valence bandX-ray photoelectron spectroscopy. Changes in band structures of stacked nano sheets of different thick-nesses are analyzed in connection to known hybridization regions of TiC and TiO2that affect elastic andtransport properties. By employing high excitation energy, the photoelectron cross-section for the C 2s– Ti 3d hybridization region at the bottom of the valence band is enhanced. As shown in this work, theO 2p and F 2p bands strongly depend both on the bond lengths to the surface groups and the adsorptionsites. The effect of surface oxidation and Ar+sputtering on the electronic structure is also discussed.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
MXene, 2D materials, Valence band, X-ray photoelecton spectroscopy, XPS, Chemical bonding, Termination species
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-145690 (URN)10.1016/j.elspec.2017.09.006 (DOI)000428825400006 ()2-s2.0-85030792688 (Scopus ID)
Available from: 2018-03-16 Created: 2018-03-16 Last updated: 2019-06-28Bibliographically approved
Magnuson, M., Tengdelius, L., Greczynski, G., Hultman, L. & Högberg, H. (2018). ­Chemical Bonding in Epitaxial ZrB2 Studied by X-ray Spectroscopy. Thin Solid Films, 649, 89-96
Open this publication in new window or tab >>­Chemical Bonding in Epitaxial ZrB2 Studied by X-ray Spectroscopy
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2018 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 649, p. 89-96Article in journal (Refereed) Published
Abstract [en]

The chemical bonding in an epitaxial ZrB2 film is investigated by Zr K-edge (1s) X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopies and compared to the ZrB2 compound target from which the film was synthesized as well as a bulk α-Zr reference. Quantitative analysis of X-ray Photoelectron Spectroscopy spectra reveals at the surface: ~5% O in the epitaxial ZrB2 film, ~19% O in the ZrB2 compound target and ~22% O in the bulk α-Zr reference after completed sputter cleaning. For the ZrB2 compound target, X-ray diffraction (XRD) shows weak but visible   11, 111, and 220 peaks from monoclinic ZrO2 together with peaks from ZrB2 and where the intensity distribution for the ZrB2 peaks show a randomly oriented target material.  For the bulk α-Zr reference no peaks from any crystalline oxide were visible in the diffractogram recorded from the 0001-oriented metal. The Zr K-edge absorption from the two ZrB2 samples demonstrate more pronounced oscillations for the epitaxial ZrB2 film than in the bulk ZrB2 attributed to the high atomic ordering within the columns of the film. The XANES exhibits no pre-peak due to lack of p-d hybridization in ZrB2, but with a chemical shift towards higher energy of 4 eV in the film and 6 eV for the bulk compared to α-Zr (17.993 keV) from the charge-transfer from Zr to B. The 2 eV larger shift in bulk ZrB2 material suggests higher oxygen content than in the epitaxial film, which is supported by XPS. In EXAFS, the modelled cell-edge in ZrB2 is slightly smaller in the thin film (a=3.165 Å, c=3.520 Å) in comparison to the bulk target material (a=3.175 Å, c=3.540 Å) while in hexagonal closest-packed metal (α-phase, a=3.254 Å, c=5.147 Å). The modelled coordination numbers show that the EXAFS spectra of the epitaxial ZrB2 film is highly anisotropic with strong in-plane contribution, while the bulk target material is more isotropic. The Zr-B distance in the film of 2.539 Å is in agreement with the calculated value from XRD data of 2.542 Å. This is slightly shorter compared to that in the ZrB2 compound target 2.599 Å, supporting the XANES results of a higher atomic order within the columns of the film compared to bulk ZrB2.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Zirconium boride, thin films, bond distances, chemical bonding, X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-144578 (URN)10.1016/j.tsf.2018.01.021 (DOI)000427524100015 ()
Note

Funding agencies: Swedish Energy Research [43606-1]; Swedish Foundation for Strategic Research (SSF) through the synergy grant FUNCASE [RMA11-0029]; Carl Trygger Foundation [CTS16:303, CTS14:310]; Swedish Research Council (VR) [621-2010 3921]; Knut and Alice Wallenberg Fou

Available from: 2018-01-29 Created: 2018-01-29 Last updated: 2018-11-29Bibliographically approved
Magnuson, M., Schmitt, T. & Duda, L. (2018). Polarization-dependent resonant inelastic X-ray scattering study atthe Cu L and O K-edges of YBa2Cu3O7-x. Journal of Electron Spectroscopy and Related Phenomena, 224, 38-44
Open this publication in new window or tab >>Polarization-dependent resonant inelastic X-ray scattering study atthe Cu L and O K-edges of YBa2Cu3O7-x
2018 (English)In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 224, p. 38-44Article in journal (Refereed) Published
Abstract [en]

We present a study on the high-Tc superconductor (HTSC) YBa2Cu3O7-x(YBCO) using polarization-dependent X-ray absorption and resonant inelastic X-ray scattering. High-resolution measurementsusing synchrotron-radiation are compared with calculations using a quasi-atomic multiplet approachperformed at the Cu 2p3/2-edge of YBCO. We use a multiplet approach within the single impurity Ander-son model to reproduce and understand the character of the localized low-energy excitations in YBCO.We observe a distinct peak at about 0.5 eV in O K RIXS. This peak shows dependence on doping, incidentenergy, and momentum transfer that suggests that it has a different origin than the previously discussedcuprate bimagnons. Therefore, we assign it to bimagnon excitations within the Zhang Rice bands and/orthe Upper Hubbard bands, respectively.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
H-Tc superconductors, YBCO, cuprates, RIXS
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-145691 (URN)10.1016/j.elspec.2017.07.005 (DOI)000428825400008 ()2-s2.0-85029521510 (Scopus ID)
Available from: 2018-03-16 Created: 2018-03-16 Last updated: 2018-11-29Bibliographically approved
Magnuson, M., Eriksson, F., Hultman, L. & Högberg, H. (2017). Bonding Structures of ZrHx Thin Films by X-ray Spectroscopy. The Journal of Physical Chemistry C, 121, 25750-25758
Open this publication in new window or tab >>Bonding Structures of ZrHx Thin Films by X-ray Spectroscopy
2017 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, p. 25750-25758Article in journal (Refereed) Published
Abstract [en]

The variation in local atomic structure and chemical bonding of ZrHx (x=0.15, 0.30, 1.16) magnetron sputtered thin films are investigated by Zr K-edge (1s) X-ray absorption near-edge structure and extended X-ray absorption fine structure spectroscopies. A chemical shift of the Zr K-edge towards higher energy with increasing hydrogen content is observed due to charge-transfer and an ionic or polar covalent bonding component between the Zr 4d and the H 1s states with increasing valency for Zr. We find an increase in the Zr-Zr bond distance with increasing hydrogen content from 3.160 Å in the hexagonal closest-packed metal (a-phase) to 3.395 Å in the understoichiometric d-ZrHx film (CaF2-type structure) with x=1.16 that largely resembles that of bulk d-ZrH2. For yet lower hydrogen contents, the structures are mixed a- and d-phases, while sufficient hydrogen loading (x>1) yields a pure δ-phase that is understoichiometric, but thermodynamically stable. The change in the hydrogen content and strain is discussed in relation to the corresponding change of bond lengths, hybridizations, and trends in electrical resistivity.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-143207 (URN)10.1021/acs.jpcc.7b03223 (DOI)000416496200016 ()
Funder
Swedish Energy Agency, 43606-1Swedish Foundation for Strategic Research , FUNCASE [RMA11-0029]Carl Tryggers foundation , CTS16:303, CTS14:310
Note

Funding agencies: Swedish Government Strategic Research Area in Materials Science on Functiona

Available from: 2017-11-23 Created: 2017-11-23 Last updated: 2018-06-04
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ORCID iD: ORCID iD iconorcid.org/0000-0002-0317-0190

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