| Publikationsliste von Dr. Katharina Ollefs |
| 2025 |
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31 - Effect of high energy ball milling, heat treatment and spark plasma sintering on structure, composition, thermal stability and magnetism in CoCrFeNiGax (x = 0.5; 1) high entropy alloys
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N.F. Shkodich, T. Smoliarova, H. Ali, B. Eggert, Z. Rao, M. Spasova, I. Tarasov, H. Wende, K. Ollefs, B. Gault, M. Farle
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Acta Materialia 284, 120569 (2025) DOI: 10.1016/j.actamat.2024.120569
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| 2023 |
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30 - Formation of precipitates in off-stoichiometric Ni-Mn-Sn Heusler alloys probed through the induced Sn-moment
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B. Eggert, A. Çakir, D. Günzing, N. Josten, F. Scheibel, R. A. Brand, M. Farle, M. Acet, H. Wende, and K. Ollefs
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RSC Advances 13, 18217-18222 (2023) DOI: 10.1039/D3RA01420G
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29 - Spatially-resolved dynamic sampling of different phasic magnetic resonances of nanoparticle ensembles in a magnetotactic bacterium Magnetospirillum Magnetotacticum
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T. Feggeler, J. Lill, D. Günzing, R. Meckenstock, D. Spoddig, M. V. Efremova, S. Wintz, M. Weigand, B. W. Zingsem, M. Farle, H. Wende, K. J. Ollefs, Hendrik Ohldag
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New Journal of Physic NJP-115578.R1, (2023) DOI: 10.1088/1367-2630/acc81f
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28 - Evaluation protocol for revealing magnonic contrast in TR-STXM measurements
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B. Zingsem, Thomas Feggeler, Ralf Meckenstock, Detlef Spoddig, Taddäus Schaffers, Santa Pile, Hendrik Ohldag, Michael Farle, Heiko Wende, Andreas Ney, Katharina Ollefs
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AIP Advances 13, (2023) DOI: 10.1063/5.0145753
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| 2022 |
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27 - Element-specific visualization of dynamic magnetic coupling in a Co/Py bilayer microstructure
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T. Feggeler, Ralf Meckenstock, Detlef Spoddig, Christian Schoeppner, Benjamin Zingsem, Taddaeus Schaffers, Hendrik Ohldag, Heiko Wende, Michael Farle, Andreas Ney, Katharina Ollefs
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Scientific Reports 12, 18724 (2022) DOI: 10.1038/s41598-022-23273-y
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| 2021 |
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26 - Spatially resolved GHz magnetization dynamics of a magnetite nano-particle chain inside a magnetotactic bacterium
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Thomas Feggeler, Ralf Meckenstock, Detlef Spoddig, Benjamin W. Zingsem, Hendrik Ohldag, Heiko Wende, Michael Farle, Michael Winklhofer and Katharina Ollefs
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Physical Review Research 3, 033036 (2021) DOI: 10.1103/PhysRevResearch.3.033036
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| 2020 |
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25 - Non-standing spin-waves in confined micrometer-sized ferromagnetic structures under uniform excitation
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S. Pile, T. Feggeler, T. Schaffers, R. Meckenstock, M. Buchner, D. Spoddig, B. Zingsem, V. Ney, M. Farle, H. Wende, H. Ohldag, A. Ney and K. Ollefs
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Applied Physics Letters 116(7), 072401-1 (2020) DOI: 10.1063/1.5139881
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| 2019 |
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24 - Extracting the Dynamic Magnetic Contrast in Time-Resolved X-Ray Transmission Microscopy
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T. Schaffers, T. Feggeler, S. Pile, R. Meckenstock, M. Buchner, D. Spoddig, V. Ney, M. Farle, H. Wende, S. Wintz, M. Weigand, H. Ohldag, K. Ollefs and A. Ney
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Nanomaterials-Basel 9(7), 940 (2019) DOI: 10.3390/nano9070940
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| 2018 |
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23 - Hysteresis Design of Magnetocaloric Materials - From Basic Mechanisms to Applications
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F. Scheibel, T. Gottschall, A. Taubel, M. Fries, K. P. Skokov, A. Terwey, W. Keune, K. Ollefs, H. Wende, M. Farle, M. Acet, O. Gutfleisch, M. E. Gruner
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Energy Technol. 6, 1397 (2018) DOI: 10.1002/ente.201800264
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| 2017 |
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22 - The combination of micro-resonators with spatially resolved ferromagnetic resonance
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T. Schaffers, R. Meckenstock, D. Spoddig, T. Feggeler, K. Ollefs, C. Schppner, S. Bonetti, H. Ohldag, M. Farle, and A. Ney
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Rev. Sci. Instrum. 88, 093703 (2017) DOI: 10.1063/1.4996780
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| 2015 |
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21 - Toward broad-band x-ray detected ferromagnetic resonance in longitudinal geometry
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K. Ollefs, R. Meckenstock, D. Spoddig, F. M. Rmer, Ch. Hassel, Ch. Schppner, V. Ney, M. Farle, A. Ney
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Journal of Applied Physics 117, 223906 (2015) DOI: 10.1063/1.4922248
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20 - Magnetic ordering in magnetic shape memory alloy Ni-Mn-In-Co
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K. Ollefs, Ch. Schppner, I. Titov, R. Meckenstock, F. Wilhelm, A. Rogalev, J. Liu, O. Gutfleisch, M. Farle, H. Wende, and M. Acet
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Physical Review B 92, 224429 (2015)
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19 - Microwave soft x-ray microscopy for nanoscale magnetization dynamics in the 510 GHz frequency range
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Stefano Bonetti, Roopali Kukreja, Zhao Chen, Detlef Spoddig, Katharina Ollefs, Christian Schppner, Ralf Meckenstock, Andreas Ney, Jude Pinto, Richard Houanche, Josef Frisch, Joachim Sthr, Hermann A. Drr, Hendrik Ohldag
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Rev. Sci. Instrum. 86, 093703 (2015) DOI: 10.1063/1.4930007
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| 2012 |
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18 - Structural and magnetic analysis of epitaxial films of Gd-doped ZnO
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V. Ney, S. Ye, T. Kammermeier, K. Ollefs, F. Wilhelm, A. Rogalev, S. Lebgue, A. L. da Rosa, and A. Ney
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Phys. Rev. B 85, 235203 (2012) DOI: 10.1103/PhysRevB.85.235203
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17 - Effects of the Inhomogenous Co Doping on the Magnetoresistance of Zn1−xCoxO Epitaxial Films
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S. Ye, L. Klar, A. Ney, V. Ney, T. Kammermeier, K. Ollefs, F. Liu and G. Wang
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Journal of Nanoscience and Nanotechnology 2, 1054 (2012) DOI: 10.1166/jnn.2012.4266
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| 2011 |
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16 - Structural, chemical and magnetic properties of secondary phases in Co-doped ZnO
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A. Ney, A. Kovcs, V. Ney, S. Ye, K. Ollefs, T. Kammermeier, F. Wilhelm, A. Rogalev and R. E. Dunin-Borkowski
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New J. Phys. 13, 103001 (2011) DOI: 10.1088/1367-2630/13/10/103001
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15 - Element-Specific Magnetic Hysteresis of Individual 18 nm Fe Nanocubes
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F. Kronast, N. Friedenberger, K. Ollefs, S. Gliga, L. Tati-Bismaths, R. Thies, A. Ney, R. Weber, C. Hassel, F. M. Rmer, A. V. Trunova, C. Wirtz, R. Hertel, H. A. Drr and M. Farle
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Nano Lett. 11, 1710 (2011) DOI: 10.1021/nl200242c
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| 2010 |
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14 - Co-Doped ZnO Epitaxial Films: From a Brillouin-Like Paramagnet to a Phase-Separated Superparamagnetic Ensemble
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V. Ney, S. Ye, K. Ollefs, T. Kammermeier, F. Wilhelm, A. Rogalev, and A. Ney
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J. Nanosci. Nanotechnol. 10, 5958 (2010) DOI: 10.1166/jnn.2010.2590
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13 - Magnetism of Co doped ZnO with Al codoping: Carrier-induced mechanisms versus extrinsic origins
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A. Ney, V. Ney, S. Ye, K. Ollefs, T. Kammermeier, T. C. Kaspar, S. A. Chambers, F. Wilhelm and A. Rogalev
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Phys. Rev. B 82, 041202(R) (2010) DOI: 10.1103/PhysRevB.82.041202
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12 - High-resolution x-ray lensless imaging by differential holographic encoding
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D. Zhu, M. Guizar- Sicairos, B. Wu, A. Scherz, Y. Acremann, T. Tyliszczak, P. Fischer, N. Friedenberger, K. Ollefs, M. Farle, J. R. Fienup, and J. Stohr
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Phys. Rev. Lett. 105, 043901 (2010) DOI: 10.1103/PhysRevLett.105.043901
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11 - Influence of the developing magnetic order on the transport properties of epitaxial Zn1-xCoxO films
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S. Ye, V. Ney, T. Kammermeier, K. Ollefs, S. Zhou, H. Schmidt, A. Ney
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J. Phys.: Conference Series 200, 052034 (2010) DOI: 10.1088/1742-6596/200/5/052034
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10 - Anisotropic paramagnetism of Co-doped ZnO epitaxial films
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A. Ney, T. Kammermeier, K. Ollefs, S. Ye, V. Ney, T. C. Kaspar, S. A. Chambers, F. Wilhelm and A. Rogalev
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Phys. Rev. B 81, 054420 (2010) DOI: 10.1103/PhysRevB.81.054420
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9 - Advanced spectroscopic synchrotron techniques to unravel the intrinsic properties of dilute magnetic oxides: the case of Co:ZnO
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A. Ney, M. Opel, T. C. Kaspar, V. Ney, S. Ye, K. Ollefs, T. Kammermeier, S. Bauer, K.-W. Nielsen, S. T. B. Goennenwein, M. H. Engelhard, S. Zhou, K. Potzger, J. Simon, W. Mader, S. M. Heald, J. C. Cezar, F. Wilhelm, A. Rogalev, R. Gross and S. A. Chambers
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New J. Phys. 12, 013020 (2010) DOI: 10.1088/1367-2630/12/1/013020
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8 - Tuning the magnetic properties of Zn1-xCoxO films
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V. Ney, S. Ye, T. Kammermeier, K. Ollefs, A. Ney, T.C. Kaspar, S.A. Chambers, F. Wilhelm and A. Rogalev
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J. Magn. Magn. Mater. 322, 1232 (2010) DOI: 10.1016/j.jmmm.2009.04.024
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7 - Gd-doped GaN studied with element specifity: very small polarization of Ga, paramagnetism of Gd and the formation of magnetic clusters
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A. Ney, T. Kammermeier, K. Ollefs, V. Ney, S. Ye, S. Dhar, K. H. Ploog, M. Rver, J. Malindretos, A. Rizzi, F. Wilhelm, A. Rogalev
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J. Magn. Magn. Mater. 322, 1162 (2010) DOI: 10.1016/j.jmmm.2009.06.033
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6 - Observation of the Onset of Magnetic Clustering in Superparamagnetic Zn1-xCoxO Films
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S. Ye, V. Ney , T. Kammermeier, K. Ollefs, A. Ney, F. Wilhelm and A. Rogalev
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J. Supercond. Nov. Magn. 23, 91 (2010) DOI: 10.1007/s10948-009-0566-6
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| 2009 |
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5 - Absence of ferromagnetic-transport signatures in epitaxial paramagnetic and superparamagnetic Zn0.95Co0.05O films
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S. Ye, V. Ney, T. Kammermeier, K. Ollefs, S. Zhou, H. Schmidt, F. Wilhelm, A. Rogalev, and A. Ney
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Phys. Rev. B 80, 245321 (2009) DOI: 10.1103/PhysRevB.80.245321
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4 - Element specific measurements of the structural properties and magnetism of CoxZn1-xO
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T. Kammermeier, V. Ney, S. Ye, K. Ollefs, T. C. Kaspar, S. A. Chambers, F.Wilhelm, A. Rogalev, and A. Ney
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J. Magn. Magn. Mater. 321, 699 (2009) DOI: 10.1016/j.jmmm.2008.11.028
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| 2008 |
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3 - Limitations of measuring small magnetic signals of samples deposited on a diamagnetic substrate
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A. Ney, T. Kammermeier, V. Ney, K. Ollefs, and S. Ye
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J. Magn. Magn. Mater. 320, 3341 (2008) DOI: 10.1016/j.jmmm.2008.07.008
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2 - Element specific magnetic properties of Gd:GaN: very small polarization of Ga and paramagnetism of Gd
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A. Ney, T. Kammermeier, V. Ney, S. Ye, K. Ollefs, E. Manuel, S. Dhar, K. H. Ploog, E. Arenholz, F. Wilhelm, and A. Rogalev
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Phys. Rev. B 77, 233308 (2008) DOI: 10.1103/PhysRevB.77.233308
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1 - Absence of intrinsic ferromagnetic interactions of isolated and paired Co dopant atoms in Zn1-xCoxO with high structural perfection
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A. Ney, K. Ollefs, S. Ye, T. Kammermeier, V. Ney, T. C. Kaspar, S. A. Chambers, F. Wilhelm, and A. Rogalev
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Phys. Rev. Lett. 100, 157201 (2008) DOI: 10.1103/PhysRevLett.100.157201
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