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Author |
Werner, R.; Raisch, C.; Leca, V.; Ion, V.; Bals, S.; Van Tendeloo, G.; Chasse, T.; Kleiner, R.; Koelle, D. |
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Title |
Transport, magnetic, and structural properties of La0.7Ce0.3MnO3 thin films: evidence for hole-doping |
Type |
A1 Journal article |
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Year  |
2009 |
Publication |
Physical review : B : solid state |
Abbreviated Journal |
Phys Rev B |
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Volume |
79 |
Issue |
5 |
Pages |
054416,1-054416,8 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Cerium-doped manganite thin films were grown epitaxially by pulsed laser deposition at 720 °C and oxygen pressure pO2=125 Pa and were subjected to different annealing steps. According to x-ray diffraction (XRD) data, the formation of CeO2 as a secondary phase could be avoided for pO28 Pa. However, transmission electron microscopy shows the presence of CeO2 nanoclusters even in those films which appear to be single phase in XRD. With O2 annealing, the metal-to-insulator transition temperature increases, while the saturation magnetization decreases and stays well below the theoretical value for electron-doped La0.7Ce0.3MnO3 with mixed Mn3+/Mn2+ valences. The same trend is observed with decreasing film thickness from 100 to 20 nm, indicating a higher oxygen content for thinner films. Hall measurements on a film which shows a metal-to-insulator transition clearly reveal holes as dominating charge carriers. Combining data from x-ray photoemission spectroscopy, for determination of the oxygen content, and x-ray absorption spectroscopy (XAS), for determination of the hole concentration and cation valences, we find that with increasing oxygen content the hole concentration increases and Mn valences are shifted from 2+ to 4+. The dominating Mn valences in the films are Mn3+ and Mn4+, and only a small amount of Mn2+ ions can be observed by XAS. Mn2+ and Ce4+ XAS signals obtained in surface-sensitive total electron yield mode are strongly reduced in the bulk-sensitive fluorescence mode, which indicates hole-doping in the bulk for those films which do show a metal-to-insulator transition. |
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Thesis |
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Publisher |
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Place of Publication |
Lancaster, Pa |
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Wos |
000263815400057 |
Publication Date |
2009-02-13 |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
25 |
Open Access |
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Notes |
Esteem 026019; Fwo |
Approved |
Most recent IF: 3.836; 2009 IF: 3.475 |
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Call Number |
UA @ lucian @ c:irua:76221 |
Serial |
3725 |
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Author |
Leca, V.; Blank, D.H.A.; Rijnders, G.; Bals, S.; Van Tendeloo, G. |
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Title |
Superconducting single-phase Sr1-xLaxCuO2 thin films with improved crystallinity grown by pulsed laser deposition |
Type |
A1 Journal article |
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Year |
2006 |
Publication |
Applied physics letters |
Abbreviated Journal |
Appl Phys Lett |
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Volume |
89 |
Issue |
9 |
Pages |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Sr1-xLaxCuO2-delta (x=0.10-0.20) thin films exhibiting an oxygen-deficient 2 root 2a(p)x2 root a(p) x c structure (a(p) and c represent the cell parameters of the perovskite subcell) were epitaxially grown by means of pulsed laser deposition in low-pressure oxygen ambient. (001) KTaO3 and (001) SrTiO3 single crystals were used as substrates, with BaTiO3 as buffer layer. The Sr1-xLaxCuO2-delta films were oxidized during cooling down in order to yield the infinite-layer-type structure. By applying this method, high quality single-phase Sr1-xLaxCuO2 thin films could be obtained for 0.10 <= x <= 0.175 doping range. The films grown on BaTiO3/KTaO3 show superconductivity for 0.15 <= x <= 0.175 with optimum doping at x=0.15, in contrast with previously reported data. (c) 2006 American Institute of Physics. |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
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Wos |
000240236600077 |
Publication Date |
2006-08-31 |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0003-6951; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.411 |
Times cited |
32 |
Open Access |
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Notes |
Fom; Fwo |
Approved |
Most recent IF: 3.411; 2006 IF: 3.977 |
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Call Number |
UA @ lucian @ c:irua:60817 |
Serial |
3366 |
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Author |
Bals, S.; Van Tendeloo, G.; Rijnders, G.; Huijben, M.; Leca, V.; Blank, D.H.A. |
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Title |
Transmission electron microscopy on interface engineered superconducting thin films |
Type |
A1 Journal article |
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Year |
2003 |
Publication |
IEEE transactions on applied superconductivity |
Abbreviated Journal |
Ieee T Appl Supercon |
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Volume |
13 |
Issue |
2:3 |
Pages |
2834-2837 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Transmission electron microscopy is used to evaluate different deposition techniques, which optimize the microstructure and physical properties of superconducting thin films. High-resolution electron microscopy proves that the use of an YBa2Cu2Ox buffer layer can avoid a variable interface configuration in YBa2Cu3O7-delta thin films grown on SrTiO3. The growth can also be controlled at an atomic level by, using sub-unit cell layer epitaxy, which results in films with high quality and few structural defects. Epitaxial strain in Sr0.85La0.15CuO2 infinite layer thin films influences the critical temperature of these films, as well as the microstructure. Compressive stress is released by a modulated or a twinned microstructure, which eliminates superconductivity. On the other hand, also tensile strain seems to lower the critical temperature of the infinite layer. |
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Place of Publication |
New York, N.Y. |
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Language |
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Wos |
000184242400101 |
Publication Date |
2003-07-16 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1051-8223; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
13 |
Open Access |
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Notes |
Iuap V-1; Fwo |
Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:103292 |
Serial |
3712 |
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Author |
Bals, S.; Van Tendeloo, G.; Rijnders, G.; Blank, D.H.A.; Leca, V.; Salluzzo, M. |
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Title |
Optimisation of superconducting thin films by TEM |
Type |
A1 Journal article |
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Year |
2002 |
Publication |
Physica: C : superconductivity |
Abbreviated Journal |
Physica C |
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Volume |
372/376 |
Issue |
part 2 |
Pages |
711-714 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
High-resolution electron microscopy is used to study the initial growth of different REBa2CU3O7-5 thin films. In DyBa2CU3O7-5 ultra-thin films, deposited on TiO2 terminated SrTiO3, two different types of interface arrangements occur: bulk-SrO-TiO2-BaO-CuO-BaO-CuO2-Dy-CuO2-BaO-bulk and bulk-SrO-TiO2-BaO-CuO2-Dy-CuO2-BaO-CuO-BaO-bulk. This variable growth sequence is the origin of the presence of antiphase boundaries. In Nd1+xBa2-xCu3O7-5 thin films, antiphase boundaries tend to annihilate by the insertion of extra Nd-layers. This annihilation is correlated with the flat morphology of the film and the absence of growth spirals at the surface of the Nd-rich films. (C) 2002 Elsevier Science B.V. All rights reserved. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Amsterdam |
Editor |
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Language |
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Wos |
000178018800033 |
Publication Date |
2002-08-26 |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0921-4534; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.404 |
Times cited |
6 |
Open Access |
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Notes |
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Approved |
Most recent IF: 1.404; 2002 IF: 0.912 |
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Call Number |
UA @ lucian @ c:irua:54796 |
Serial |
2485 |
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