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Leedahl B, Boukhvalov DW, Kurmaev EZ, Kukharenko A, Zhidkov IS, Gavrilov NV, Cholakh SO, Le PH, Luo CW, Moewes A. Bulk vs. Surface Structure of 3d Metal Impurities in Topological Insulator Bi 2Te 3. Sci Rep 2017; 7:5758. [PMID: 28720873 PMCID: PMC5515884 DOI: 10.1038/s41598-017-06069-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 06/07/2017] [Indexed: 11/09/2022] Open
Abstract
Topological insulators have become one of the most prominent research topics in materials science in recent years. Specifically, Bi2Te3 is one of the most promising for technological applications due to its conductive surface states and insulating bulk properties. Herein, we contrast the bulk and surface structural environments of dopant ions Cr, Mn, Fe, Co, Ni, and Cu in Bi2Te3 thin films in order to further elucidate this compound. Our measurements show the preferred oxidation state and surrounding crystal environment of each 3d-metal atomic species, and how they are incorporated into Bi2Te3. We show that in each case there is a unique interplay between structural environments, and that it is highly dependant on the dopant atom. Mn impurities in Bi2Te3 purely substitute into Bi sites in a 2+ oxidation state. Cr atoms seem only to reside on the surface and are effectively not able to be absorbed into the bulk. Whereas for Co and Ni, an array of substitutional, interstitial, and metallic configurations occur. Considering the relatively heavy Cu atoms, metallic clusters are highly favourable. The situation with Fe is even more complex, displaying a mix of oxidation states that differ greatly between the surface and bulk environments.
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Mallineni SSK, Boukhvalov DW, Zhidkov IS, Kukharenko AI, Slesarev AI, Zatsepin AF, Cholakh SO, Rao AM, Serkiz SM, Bhattacharya S, Kurmaev EZ, Podila R. Influence of dopants on the impermeability of graphene. NANOSCALE 2017; 9:6145-6150. [PMID: 28447704 DOI: 10.1039/c7nr00949f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Graphene has attracted much attention as an impermeable membrane and a protective coating against oxidation. While many theoretical studies have shown that defect-free graphene is impermeable, in reality graphene inevitably has defects in the form of grain boundaries and vacancies. Here, we study the effects of N-dopants on the impermeability of few-layered graphene (FLG) grown on copper using chemical vapor deposition. The grain boundaries in FLG have minimal impact on their permeability to oxygen as they do not provide a continuous channel for gas transport due to high tortuosity. However, we experimentally show that the N-dopants in FLG display multiple configurations that create structural imperfections to selectively allow gas molecules to permeate. We used a comprehensive array of tools including Raman spectroscopy, X-ray photoelectron spectroscopy, optically stimulated electron emission measurements, and density functional theory of N-doped graphene on copper to elucidate the effects of dopant configuration on the impermeability of graphene. Our results clearly show that oxygen can permeate through graphene with non-graphitic nitrogen dopants that create pores in graphene and oxidize the underlying Cu substrate while graphitic nitrogen dopants do not show any changes compared to the pristine form. Furthermore, we observed that the work function of graphene can be tuned effectively by changing the dopant configuration.
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Akbulatov AF, Luchkin SY, Frolova LA, Dremova NN, Gerasimov KL, Zhidkov IS, Anokhin DV, Kurmaev EZ, Stevenson KJ, Troshin PA. Probing the Intrinsic Thermal and Photochemical Stability of Hybrid and Inorganic Lead Halide Perovskites. J Phys Chem Lett 2017; 8:1211-1218. [PMID: 28220700 DOI: 10.1021/acs.jpclett.6b03026] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report a careful and systematic study of thermal and photochemical degradation of a series of complex haloplumbates APbX3 (X = I, Br) with hybrid organic (A+ = CH3NH3) and inorganic (A+ = Cs+) cations under anoxic conditions (i.e., without exposure to oxygen and moisture by testing in an inert glovebox environment). We show that the most common hybrid materials (e.g., MAPbI3) are intrinsically unstable with respect to the heat- and light-induced stress and, therefore, can hardly sustain the real solar cell operation conditions. On the contrary, the cesium-based all-inorganic complex lead halides revealed far superior stability and, therefore, provide an impetus for creation of highly efficient and stable perovskite solar cells that can potentially achieve pragmatic operational benchmarks.
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Sowa M, Łastówka D, Kukharenko AI, Korotin DM, Kurmaev EZ, Cholakh SO, Simka W. Characterisation of anodic oxide films on zirconium formed in sulphuric acid: XPS and corrosion resistance investigations. J Solid State Electrochem 2016. [DOI: 10.1007/s10008-016-3369-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Babilas D, Urbańczyk E, Sowa M, Maciej A, Korotin DM, Zhidkov IS, Basiaga M, Krok-Borkowicz M, Szyk-Warszyńska L, Pamuła E, Kurmaev EZ, Cholakh SO, Simka W. On the electropolishing and anodic oxidation of Ti-15Mo alloy. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.01.218] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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31
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Leedahl B, Korolev AV, Zhidkov IS, Skornyakov SL, Anisimov VI, Belozerov AS, Kukharenko AI, Kurmaev EZ, Grokhovskii VI, Cholakh SO, Moewes A. Searching for pure iron in nature: the Chelyabinsk meteorite. RSC Adv 2016. [DOI: 10.1039/c6ra16598b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Herein we aimed to use thermomagnetic analysis (TMA) to determine the nature of iron and nickel in the Chelyabinsk meteorite, and their effect on the meteorite's magnetism.
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Ketabi N, de Boer T, Karakaya M, Zhu J, Podila R, Rao AM, Kurmaev EZ, Moewes A. Tuning the electronic structure of graphene through nitrogen doping: experiment and theory. RSC Adv 2016. [DOI: 10.1039/c6ra07546k] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Tuning the electronic properties of graphene by doping atoms into its lattice makes it more applicable for electronic devices.
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McLeod JA, Pitman AL, Kurmaev EZ, Finkelstein LD, Zhidkov IS, Savva A, Moewes A. Linking the HOMO-LUMO gap to torsional disorder in P3HT/PCBM blends. J Chem Phys 2015; 143:224704. [DOI: 10.1063/1.4936898] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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34
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Bazylewski PF, Nguyen VL, Bauer RPC, Hunt AH, McDermott EJG, Leedahl BD, Kukharenko AI, Cholakh SO, Kurmaev EZ, Blaha P, Moewes A, Lee YH, Chang GS. Selective Area Band Engineering of Graphene using Cobalt-Mediated Oxidation. Sci Rep 2015; 5:15380. [PMID: 26486966 PMCID: PMC4614253 DOI: 10.1038/srep15380] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 09/23/2015] [Indexed: 11/09/2022] Open
Abstract
This study reports a scalable and economical method to open a band gap in single layer graphene by deposition of cobalt metal on its surface using physical vapor deposition in high vacuum. At low cobalt thickness, clusters form at impurity sites on the graphene without etching or damaging the graphene. When exposed to oxygen at room temperature, oxygen functional groups form in proportion to the cobalt thickness that modify the graphene band structure. Cobalt/Graphene resulting from this treatment can support a band gap of 0.30 eV, while remaining largely undamaged to preserve its structural and electrical properties. A mechanism of cobalt-mediated band opening is proposed as a two-step process starting with charge transfer from metal to graphene, followed by formation of oxides where cobalt has been deposited. Contributions from the formation of both CoO and oxygen functional groups on graphene affect the electronic structure to open a band gap. This study demonstrates that cobalt-mediated oxidation is a viable method to introduce a band gap into graphene at room temperature that could be applicable in electronics applications.
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Green RJ, Regier TZ, Leedahl B, McLeod JA, Xu XH, Chang GS, Kurmaev EZ, Moewes A. Adjacent Fe-Vacancy Interactions as the Origin of Room Temperature Ferromagnetism in (In(1-x)Fe(x))2O3. PHYSICAL REVIEW LETTERS 2015; 115:167401. [PMID: 26550901 DOI: 10.1103/physrevlett.115.167401] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Indexed: 06/05/2023]
Abstract
Dilute magnetic semiconductors (DMSs) show great promise for applications in spin-based electronics, but in most cases continue to elude explanations of their magnetic behavior. Here, we combine quantitative x-ray spectroscopy and Anderson impurity model calculations to study ferromagnetic Fe-substituted In2O3 films, and we identify a subset of Fe atoms adjacent to oxygen vacancies in the crystal lattice which are responsible for the observed room temperature ferromagnetism. Using resonant inelastic x-ray scattering, we map out the near gap electronic structure and provide further support for this conclusion. Serving as a concrete verification of recent theoretical results and indirect experimental evidence, these results solidify the role of impurity-vacancy coupling in oxide-based DMSs.
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Endo K, Hyodo K, Takaoka K, Ida T, Shimada S, Takagi Y, Kurmaev EZ. Analysis of valence XPS and AES of C, N, O, and F-containing substances by DFT calculations using the model molecules. Chem Phys 2015. [DOI: 10.1016/j.chemphys.2015.03.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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37
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McLeod JA, Kurmaev EZ, Perez I, Green RJ, Xing LY, Wang XC, Jin CQ, Moewes A. Electronic structure and spin trapping in LiMnAs and LiFeAs:Mn. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:015504. [PMID: 25478917 DOI: 10.1088/0953-8984/27/1/015504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The electronic structure of insulating antiferromagnetic LiMnAs is investigated using soft x-ray spectroscopy and compared to the electronic structure of metallic LiFeAs. Our calculations support the experimentally observed insulating antiferromagnetic order in LiMnAs. The x-ray absorption and resonant inelastic x-ray scattering spectra in LiFeAs and LiMnAs are adequately explained by the electronic structure alone, although it is possible that LiMnAs has significant electronic correlations driven by Hund's J coupling. Finally, we show evidence of a possible spin trap in Li(Fe0.95Mn0.05)As.
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Hunt A, Kurmaev EZ, Moewes A. A re-evaluation of how functional groups modify the electronic structure of graphene oxide. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:4870-4874. [PMID: 24903059 DOI: 10.1002/adma.201401300] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Revised: 04/14/2014] [Indexed: 06/03/2023]
Abstract
The first 4 eV of the conduction band in graphene oxide is dominated by states from carbon sites that are in close proximity, but not directly bonded, to oxidizing functional groups. The carbon sites that are bonded directly to these groups, such as epoxide and hydroxyl groups, are much higher in energy.
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Kazek-Kęsik A, Dercz G, Kalemba I, Suchanek K, Kukharenko AI, Korotin DM, Michalska J, Krząkała A, Piotrowski J, Kurmaev EZ, Cholakh SO, Simka W. Surface characterisation of Ti–15Mo alloy modified by a PEO process in various suspensions. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2014; 39:259-72. [DOI: 10.1016/j.msec.2014.03.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 02/12/2014] [Accepted: 03/02/2014] [Indexed: 11/16/2022]
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Korotin MA, Pchelkina ZV, Skorikov NA, Kurmaev EZ, Anisimov VI. The coherent potential approximation for strongly correlated systems: electronic structure and magnetic properties of NiO-ZnO solid solutions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:115501. [PMID: 24589676 DOI: 10.1088/0953-8984/26/11/115501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A method of electronic structure calculations for strongly correlated disordered materials is developed employing the basic idea of the coherent potential approximation. The evolution of the electronic structure and spin magnetic moment value with the concentration x in strongly correlated Ni1-xZnxO solid solutions is investigated in the framework of this method. The values of the energy gap and magnetic moment obtained are in agreement with the available experimental data.
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Simka W, Krząkała A, Korotin DM, Zhidkov IS, Kurmaev EZ, Cholakh SO, Kuna K, Dercz G, Michalska J, Suchanek K, Gorewoda T. Modification of a Ti–Mo alloy surface via plasma electrolytic oxidation in a solution containing calcium and phosphorus. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.02.102] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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42
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Korotin DM, Bartkowski S, Kurmaev EZ, Neumann M, Yakushina EB, Valiev RZ, Cholakh SO. Surface studies of coarse-grained and nanostructured titanium implants. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2012; 12:8567-8572. [PMID: 23421245 DOI: 10.1166/jnn.2012.6806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The results of XPS measurements of nanostructured Ti (ns-Ti) prepared with a help of severe plastic deformation (SPD) have been presented. We have measured XPS spectra of core levels (Ti 2p, O 1s, C 1s, F 1s) and valence bands before and after treatment of ns-Ti-implants in HF. The obtained data have been compared with XPS measurements of untreated and acid treated coarse-grained Ti (cg-Ti). According to these measurements the surface composition has not practically been changed by reduction of grains size of Ti-implants. It has been found that the surface of both types of implants is covered with thick TiO2 layer. The acid treatment reduces the surface contamination of ns-Ti and cg-Ti by hydrocarbons and induces better passivation and formation of more thick TiO2 layer. It has been shown that severe plastic deformation not only improves mechanical properties but also preserves corrosion stability of Ti-implants.
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McLeod JA, Buling A, Green RJ, Boyko TD, Skorikov NA, Kurmaev EZ, Neumann M, Finkelstein LD, Ni N, Thaler A, Bud'ko SL, Canfield PC, Moewes A. Effect of 3d doping on the electronic structure of BaFe2As2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:215501. [PMID: 22534111 DOI: 10.1088/0953-8984/24/21/215501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The electronic structure of BaFe(2)As(2) doped with Co, Ni and Cu has been studied by a variety of experimental and theoretical methods, but a clear picture of the dopant 3d states has not yet emerged. Herein we provide experimental evidence of the distribution of Co, Ni and Cu 3d states in the valence band. We conclude that the Co and Ni 3d states provide additional free carriers to the Fermi level, while the Cu 3d states are found at the bottom of the valence band in a localized 3d(10) shell. These findings help shed light on why superconductivity can occur in BaFe(2)As(2) doped with Co and Ni but not Cu.
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Zatsepin DA, Green RJ, Hunt A, Kurmaev EZ, Gavrilov NV, Moewes A. Structural ordering in a silica glass matrix under Mn ion implantation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:185402. [PMID: 22508933 DOI: 10.1088/0953-8984/24/18/185402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Mn(+)-implanted, amorphous SiO(2) samples were synthesized using pulsed-ion implantation without thermal annealing. The crystal and electronic structures have been studied using x-ray diffraction and synchrotron-based soft x-ray absorption and emission spectroscopy at the Si and Mn L(2,3) edges. We find a combination of small MnO clusters and Si crystallites at shallow depths while tetrahedral Mn coordination is found deeper in the host target. Through a combination of techniques, we find that the implantation process simultaneously decreases the long-range order in the near-surface region and increases order deeper in the SiO(2) host. Our results suggest Mn substitution into Si sites at deep levels catalyzes the formation of α-quartz, providing insight into the complex interactions that determine the local structure around the impurities as well as the overall changes to the crystallinity of implanted SiO(2).
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McLeod JA, Kurmaev EZ, Sushko PV, Boyko TD, Levitsky IA, Moewes A. Selective Response of Mesoporous Silicon to Adsorbants with Nitro Groups. Chemistry 2012; 18:2912-22. [DOI: 10.1002/chem.201102084] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 11/11/2011] [Indexed: 11/05/2022]
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46
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Korotin DM, Bartkowski S, Kurmaev EZ, Meumann M, Yakushina EB, Valiev RZ, Cholakh SO. Surface Characterization of Titanium Implants Treated in Hydrofluoric Acid. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/jbnb.2012.31011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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47
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Kurmaev EZ, McLeod JA, Skorikov NA, Finkelstein LD, Moewes A, Korotin MA, Izyumov YA, Xie YL, Wu G, Chen XH. Structural models of FeSe(x). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:435702. [PMID: 21832444 DOI: 10.1088/0953-8984/21/43/435702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Two different structural models for non-stoichiometric FeSe(x) are examined and compared with soft x-ray spectroscopy findings for FeSe(x) (x = 0.85, 0.50). A structural model of tetragonal FeSe with excess interstitial Fe gives better agreement with experiment than a structural model of tetragonal FeSe with Se vacancies. This interstitial Fe increases the number of 3d states at the Fermi level. We find evidence that large non-stoichiometric ratios of Fe:Se, such as that of FeSe(0.50), yield clusters of pure Fe in the crystal structure.
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Kurmaev EZ, McLeod JA, Skorikov NA, Finkelstein LD, Moewes A, Izyumov YA, Clarke S. Identifying valence structure in LiFeAs and NaFeAs with core-level spectroscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:345701. [PMID: 21715787 DOI: 10.1088/0953-8984/21/34/345701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Resonant x-ray emission spectroscopy (XES) measurements at Fe L(2,3) edges and electronic structure calculations for LiFeAs and NaFeAs are presented. Experiment and theory show that in the vicinity of the Fermi energy, the density of states is dominated by contributions from Fe 3d states. The comparison of Fe L(2,3) XES with spectra of related FeAs compounds reveals similar trends in energy and the ratio of intensities of the L(2) and L(3) peaks (I(L(2))/I(L(3)) ratio). The I(L(2))/I(L(3)) ratio for all FeAs-based superconductors is found to be closer to that of metallic Fe than that of the strongly correlated FeO. We conclude that iron-based superconductors are weakly or, at most, moderately correlated systems.
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Chang GS, Kurmaev EZ, Boukhvalov DW, Finkelstein LD, Moewes A, Bieber H, Colis S, Dinia A. Co and Al co-doping for ferromagnetism in ZnO:Co diluted magnetic semiconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:056002. [PMID: 21817308 DOI: 10.1088/0953-8984/21/5/056002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Co and Al co-doped ZnO diluted magnetic semiconductors are fabricated by a pulsed laser deposition and their electronic structure is investigated using x-ray absorption and emission spectroscopy. The Zn(0.895)Co(0.100)Al(0.005)O thin films grown under oxygen-rich conditions exhibit ferromagnetic behavior without any indication of Co clustering. The Co L-edge and O K-edge x-ray absorption and emission spectra suggest that most of the Co dopants occupy the substitutional sites and the oxygen vacancies are not responsible for free charge carriers. The spectroscopic results and first principles calculations reveal that the ferromagnetism in Co and Al co-doped ZnO semiconductors mainly arises from Al interstitial defects and their hybridization with Co substitutional dopants.
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Chang GS, Kurmaev EZ, Finkelstein LD, Choi HK, Lee WO, Park YD, Pedersen TM, Moewes A. Post-annealing effect on the electronic structure of Mn atoms in Ga(₁-x)Mn(x)As probed by resonant inelastic x-ray scattering. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2007; 19:076215. [PMID: 22251602 DOI: 10.1088/0953-8984/19/7/076215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The electronic structure of as-grown and post-annealed Ga(₁-x)Mn(x)As epilayers (x≈0.055) has been investigated using resonant inelastic x-ray scattering. Mn L₂,₃ x-ray emission spectra show that the integral intensity ratio of Mn L₂ to L₃ emission lines increases with annealing temperature and comes close to that of manganese oxide. The oxygen K-emission/absorption spectra of post-annealed Ga₀.₉₄₅Mn₀.₀₅₅As show 1.5-3.0 times higher degree of oxidation on the film surface than that of the as-grown sample. These experimental findings are attributed to the diffusion of Mn impurity atoms from interstitial positions in the GaAs host lattice to the surface where they are passivated by oxygen.
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