Theory of spectroscopy, dynamics and numerical methods for complex materials

Publications

2020

[112] Rima Xenia Schüssler, Hendrik Bekker, Martin Braß, Halil Cakir, J.R. Crespo López-Urrutia, Menno Door, Pavel Filianin, Zoltan Harman, Maurits W. Haverkort, Wen Jia Huang, Paul Indelicato, Christoph Helmut Keitel, Charlotte Maria König, Kathrin Kromer, Marius Müller, Yuri N. Novikov, Alexander Rischka, Christoph Schweiger, Sven Sturm, Stefan Ulmer, Ssergey Eliseev, Klaus Blaum ,
// Detection of metastable electronic states by Penning trap mass spectrometry //,
Nature 581, 42 (2020), arXiv.

[111] Abhishek Nag, H. C. Robarts, F. Wenzel, J. Li, Hebatalla Elnaggar, Ru-Pan Wang, A. C. Walters, M. García-Fernández, F. M. F. de Groot, M. W. Haverkort, and Ke-Jin Zhou ,
// Many-body physics of single and double spin-flip excitations in NiO //,
Phys. Rev. Lett. 124, 067202 (2020), arXiv, .

[110] H. Elnaggar, R. Wang, S. Lafuerza, E. Paris, A. C. Komarek, H. Guo, Y. Tseng, D. McNally, F. Frati, M. W. Haverkort, M. Sikora, T. Schmitt, and F. M. F. de Groot ,
// Possible absence of trimeron correlations above the Verwey temperature in Fe₃O₄ //,
Phys. Rev. B 101, 085107 (2020), arXiv, .

2019

[109] Andrea Amorese, Oliver Stockert, Kurt Kummer, Nicholas B. Brookes, Dae-Jeong Kim, Zachary Fisk, Maurits W. Haverkort, Peter Thalmeier, Liu Hao Tjeng, and Andrea Severing ,
// Resonant inelastic x-ray scattering investigation of the crystal-field splitting of Sm³⁺ in SmB₆ //,
Phys. Rev. B 100, 241107 (2019), arXiv, .

[108] C. Velte, F. Ahrens, A. Barth, K. Blaum, M. Braß, Menno Door, H. Dorrer, Ch. E. Düllmann, S. Eliseev, C. Enss, P. Filianin, A. Fleischmann, L. Gastaldo, A. Goeggelmann, T. Day Goodacre, M.W. Haverkort, D. Hengstler, J. Jochum, K. Johnston, M. Keller, S. Kempf, T. Kieck, C.M. König, U. Köster, K. Kromer, F. Mantegazzini, B. Marsh, Yu N. Novikov, F. Piquemal, C. Riccio, D. Richter, A. Rischka, S. Rothe, R.X. Schüssler, Ch. Schweiger, T. Stora, M. Wegner, K. Wendt, M. Zampaolo, K. Zuber ,
// High-resolution and low-background ¹⁶³Ho spectrum: interpretation of the resonance tails //,
Eur. Phys. J. C 79 1026 (2019), arXiv, .

[107] Brett Leedahl, Martin Sundermann, Andrea Amorese, Andrea Severing, Hlynur Gretarsson, Lunyong Zhang, Alexander C. Komarek, Antoine Maignan, Maurits W. Haverkort, Liu Hao Tjeng ,
// Origin of Ising magnetism in Ca₃Co₂O₆ unveiled by orbital imaging //,
Nature Communications 10, 5447 (2019).

[106] H. Elnaggar, Ph. Sainctavit, A. Juhin, S. Lafuerza, F. Wilhelm, A. Rogalev, M.-A. Arrio, Ch. Brouder, M. van der Linden, Z. Kakol, M. Sikora, M.W. Haverkort, P. Glatzel, F.M.F. de Groot ,
// Noncollinear Ordering of the Orbital Magnetic Moments in Magnetite //,
Phys. Rev. Lett. 123, 207201 (2019), arXiv, .

[105] Y. Lu, X. Cao, P. Hansmann, M.W. Haverkort ,
// Natural-orbital impurity solver and projection approach for Green's functions //,
Phys. Rev. B 100, 115134 (2019), arXiv, .

[104] Hebatalla Elnaggar, Ru-Pan Wang, Sara Lafuerza, Eugenio Paris, Yi Tseng, Daniel McNally, Alexander Komarek, Maurits W. Haverkort, Marcin Sikora, Thorsten Schmitt, Frank M.F. de Groot ,
// Magnetic contrast at spin-flip excitations: An advanced X-ray spectroscopy tool to study magnetic-ordering //,
ACS Appl. Mater. Interfaces 11, 36213 (2019), arXiv, .

[103] S. Agrestini, K. Chen, C.-Y. Kuo, L. Zhao, H.-J. Lin, C.-T. Chen, A. Rogalev, P. Ohresser, T.-S. Chan, S.-C. Weng, G. Auffermann, A. Völzke, A.C. Komarek, K. Yamaura, M.W. Haverkort, Z. Hu, L.H. Tjeng ,
// Nature of the magnetism of iridium in the double perovskite Sr₂CoIrO₆ //,
Phys. Rev. B 100, 014443 (2019), arXiv, .

[102] M. Sundermann, A. Amorese, F. Strigari, B. Leedahl, L.H. Tjeng, M.W. Haverkort, H. Gretarsson, H. Yavaş, M. Moretti Sala, E.D. Bauer, P.F.S. Rosa, J.D. Thompson, A. Severing ,
// Orientation of the ground-state orbital in CeCoIn₅ and CeRhIn₅//,
Phys. Rev. B 99, 235143 (2019), arXiv, .

[101] Hasan Yavaş, Martin Sundermann, Kai Chen, Andrea Amorese, Andrea Severing, Hlynur Gretarsson, Maurits W. Haverkort, Liu Hao Tjeng ,
// Direct imaging of orbitals in quantum materials //,
Nature Physics 15, 559 (2019).

[100] K. Fürsich, Y. Lu, D. Betto, M. Bluschke, J. Porras, E. Schierle, R. Ortiz, H. Suzuki, G. Cristiani, G. Logvenov, N.B. Brookes, M.W. Haverkort, .M Le Tacon, E. Benckiser, M. Minola, B. Keimer ,
// Resonant inelastic x-ray scattering study of bond order and spin excitations in nickelate thin-film structures //,
Phys. Rev. B 99, 165124 (2019), arXiv, .

[99] Hidetomo Usui, Masayuki Ochi, Sota Kitamura, Takashi Oka, Daisuke Ogura, Helge Rosner, Maurits W. Haverkort, Veronika Sunko, Philip D.C. King, Andrew P. Mackenzie, Kazuhiko Kuroki ,
// Hidden kagome-lattice picture and origin of high conductivity in delafossite PtCoO₂ //,
Phys. Rev. Materials 3, 045002 (2019), arXiv, .

2018

[98] Hakuto Suzuki, Matteo Minola, Yi Lu, Yingying Peng, Roberto Fumagalli, Emilie Lefrançois, Toshinao Loew, Juan Porras, Kurt Kummer, Davide Betto, Shigeyuki Ishida, Hiroshi Eisaki, Cheng Hu, Xingjiang Zhou, Maurits W. Haverkort, Nicholas B. Brookes, Lucio Braicovich, Giacomo Ghiringhelli, Matthieu Le Tacon, Bernhard Keimer ,
// Probing the energy gap of high-temperature cuprate superconductors by resonant inelastic x-ray scattering //,
npj Quantum Materials 3, 65 (2018), arXiv, .

[97] M. Sundermann, G. van der Laan, A. Severing, L. Simonelli, G. H. Lander, M. W. Haverkort, and R. Caciuffo ,
// Crystal-field states of UO₂probed by directional dependence of nonresonant inelastic x-ray scattering //,
Phys. Rev. B 98, 205108 (2018), arXiv, .

[96] Andrea Amorese, Kurt Kummer, Nicholas B. Brookes, Oliver Stockert, Devashibhai T. Adroja, André M Strydom, Andrey Sidorenko, Hannes Winkler, Diego A. Zocco, Andrey Prokofiev, Silke Paschen, Maurits W. Haverkort, Liu Hao Tjeng, Andrea Severing ,
// Determining the local low-energy excitations in the Kondo semimetal CeRu₄Sn₆ using resonant inelastic x-ray scattering

//,
Phys. Rev. B 98, 081116 (2018), arXiv, .

* [95] Y. Lu, D. Betto, K. Fürsich, H. Suzuki, H.-H. Kim, G. Cristiani, G. Logvenov, N.B. Brookes, E. Benckiser, M.W. Haverkort, G. Khaliullin, M. Le Tacon, M. Minola, B. Keimer ,\\ // Site-Selective Probe of Magnetic Excitations in Rare-Earth Nickelates Using Resonant Inelastic X-ray Scattering //,\\ [[ https://doi.org/10.1103/PhysRevX.8.031014 | Phys. Rev. X 8, 031014 (2018)]], arXiv, {{ :publications:phys._rev._x_2018_lu.pdf | }}.

* [94] S. Agrestini, C.-Y. Kuo, K. Chen, Y. Utsumi, D. Mikhailova, A. Rogalev, F. Wilhelm, T. Förster, A. Matsumoto, T. Takayama, H. Takagi, M.W. Haverkort, Z. Hu, L.H. Tjeng ,\\ // Probing the J<sub>eff</sub>=0 ground state and the Van Vleck paramagnetism of the Ir<sup>5+</sup> ions in layered Sr<sub>2</sub>Co<sub>0.5</sub>Ir<sub>0.5</sub>O<sub>4</sub> //,\\ [[ https://doi.org/10.1103/PhysRevB.97.214436 | Phys. Rev. X 8, 031014 (2018)]], arXiv, {{ :publications:phys._rev._b_2018_agrestini.pdf | }}.

* [93] M. Braß, C. Enss, L. Gastaldo, R.J. Green, M.W. Haverkort,\\ // Ab initio calculation of the calorimetric electron-capture spectrum of <sup>163</sup>Ho: Intra-atomic decay into bound states //,\\ [[ https://doi.org/10.1103/PhysRevC.97.054620 | Phys. Rev. C 97, 054620 (2018)]], arXiv, {{ :publications:phys._rev._c_2018_brass.pdf | }}.

* [92] Patric Zimmermann, Robert J. Green, Maurits W. Haverkort, Frank M.F. De Groot ,\\ // Quanty4RIXS: a program for crystal field multiplet calculations of RIXS and RIXS–MCD spectra using Quanty //,\\ [[ https://doi.org/10.1107/S1600577518004058 | J. Synchrotron Rad. 25, 899 (2018)]], arXiv, {{ :publications:j._synchrotron_rad._2018_zimmermann.pdf | }}.

* [91] C.F. Chang, T.C. Koethe, Z. Hu, J. Weinen, S. Agrestini, L. Zhao, J. Gegner, H. Ott, G. Panaccione, Hua Wu, M.W. Haverkort, H. Roth, A.C. Komarek, F. Offi, G. Monaco, Y.-F. Liao, K.-D. Tsuei, H.-J. Lin, C.T. Chen, A. Tanaka, L.H. Tjeng ,\\ // c--Axis Dimer and Its Electronic Breakup: The Insulator-to-Metal Transition in Ti<sub>2</sub>O<sub>3</sub> //,\\ [[ https://doi.org/10.1103/PhysRevX.8.021004 | Phys. Rev. X 8, 021004 (2018)]], arXiv, {{ :publications:phys._rev._x_2018_chang.pdf | }}.

* [90] Martin Sundermann, Hasan Yavaş, Kai Chen, Dae Jeong Kim, Zachary Fisk, Deepa Kasinathan, Maurits W. Haverkort, P. Thalmeier, A. Severing, L.H. Tjeng ,\\ // 4f Crystal Field Ground State of the Strongly Correlated Topological Insulator SmB<sub>6</sub> //,\\ [[ https://doi.org/10.1103/PhysRevLett.120.016402 | Phys. Rev. Lett. 120, 016402 (2018)]], arXiv, {{ :publications:phys._rev._lett._2018_sundermann.pdf | }}.

2017

[89] Johann Lüder, Johan Schött, Barbara Brena, Maurits W. Haverkort, Patrik Thunström, Olle Eriksson, Biplab Sanyal, Igor Di Marco, Yaroslav O Kvashnin ,
// Theory of L-edge spectroscopy of strongly correlated systems //,
Phys. Rev. B 96, 245131 (2017), arXiv, .

[88] Yi Lu, Maurits W. Haverkort ,
// Nonperturbative series expansion of Green’s functions: the anatomy of resonant inelastic x-ray scattering in the doped Hubbard model //,
Phys. Rev. Lett. 119, 256401 (2017), arXiv, .

[87] Y. Utsumi, D. Kasinathan, K.-T. Ko, S. Agrestini, M.W. Haverkort, S. Wirth, Y.H. Wu, K.D. Tsuei, D.J. Kim, Z. Fisk, A. Tanaka, P. Thalmeier, L.H. Tjeng ,
// Bulk and surface electronic properties of SmB₆: A hard x-ray photoelectron spectroscopy study //,
Phys. Rev. B 96, 155130 (2017), arXiv, .

[86] Daisuke Ishikawa, Maurits W. Haverkort, Alfred Q.R. Baron ,
// Lattice and Magnetic Effects on a d–d Excitation in NiO Using a 25 meV Resolution X-ray Spectrometer //,
J. Phys. Soc. Jpn. 86, 093706 (2017), arXiv, .

[85] Veronika Sunko, H. Rosner, P. Kushwaha, S. Khim, F. Mazzola, L. Bawden, O.J. Clark, J.M. Riley, D. Kasinathan, M.W. Haverkort, T.K. Kim, M. Hoesch, J. Fujii, I. Vobornik, A.P. Mackenzie, P.D.C. King ,
// Maximal Rashba-like spin splitting via kinetic-energy-coupled inversion-symmetry breaking //,
Nature volume 549, 492 (2017).

[84] M. Minola, Y. Lu, Y.Y. Peng, G. Dellea, H. Gretarsson, M.W. Haverkort, Y. Ding, X. Sun, X.J. Zhou, D.C. Peets, L. Chauviere, P. Dosanjh, D.A. Bonn, R. Liang, A. Damascelli, M. Dantz, X. Lu, T. Schmitt, L. Braicovich, G. Ghiringhelli, B. Keimer, M. Le Tacon ,
// Crossover from collective to incoherent spin excitations in superconducting cuprates probed by detuned resonant inelastic X-ray scattering //,
Phys. Rev. Lett. 119, 097001 (2017), arXiv, .

[83] C.-Y. Kuo, T. Haupricht, J. Weinen, Hua Wu, K.-D. Tsuei, M.W. Haverkort, A. Tanaka, L.H. Tjeng ,
// Challenges from experiment: electronic structure of NiO //,
The European Physical Journal Special Topics 226, 2445 (2017), arXiv, .

[82] Yi Lu, Maurits W Haverkort ,
// Exact diagonalization as an impurity solver in dynamical mean field theory //,
The European Physical Journal Special Topics 226, 2549 (2017), arXiv, .

[81] Yi Lu, Zhicheng Zhong, Maurits W Haverkort, Philipp Hansmann ,
// Origins of bond and spin order in rare-earth nickelate bulk and heterostructures //,
Phys. Rev. B 95, 195117 (2017), arXiv, .

[80] Martin Sundermann, K. Chen, H Yavaş, Hanoh Lee, Zachary Fisk, M.W. Haverkort, Liu Hao Tjeng, A. Severing ,
// The quartet ground state in CeB₆: An inelastic x-ray scattering study //,
Europhysics Letters 117, 17003 (2017), arXiv, .

[79] S.S. Agrestini, C.-Y. Kuo, M. Moretti Sala, Z. Hu, D. Kasinathan, K.-T. Ko, P. Glatzel, M. Rossi, J.-D. Cafun, K.O. Kvashnina, A. Matsumoto, T. Takayama, H. Takagi, L.H. Tjeng, M.W. Haverkort ,
// Long-range interactions in the effective low energy Hamiltonian of Sr₂IrO₄. A core level resonant inelastic X-ray scattering

//,
Phys. Rev. B 95, 205123 (2017) , arXiv, .

2016

[78] Vincent Vercamer, Myrtille OJY Hunault, Gérald Lelong, Maurits W Haverkort, Georges Calas, Yusuke Arai, Hiroyuki Hijiya, Lorenzo Paulatto, Christian Brouder, Marie-Anne Arrio, Amélie Juhin ,
// Calculation of optical and K pre-edge absorption spectra for ferrous iron of distorted sites in oxide crystals

//,
Phys. Rev. B 94, 245115 (2016) , arXiv, .

[77] Martin Sundermann, Maurits W. Haverkort, Stefano Agrestini, Ali Al-Zein, Marco Moretti Sala, Yingkai Huang, Mark Golden, Anne De Visser, Peter Thalmeier, Liu Hao Tjeng, Andrea Severing ,
// Direct bulk-sensitive probe of 5f symmetry in URu₂Si₂ //,
PNAS 113, 13989 (2016) , arXiv, .

[76] Jorge E. Hamann-Borrero, Sebastian Macke, Woo Seok Choi, Ronny Sutarto, Feizhou He, Abdullah Radi, Ilya Elfimov, Robert J. Green, Maurits W. Haverkort, Volodymyr B. Zabolotnyy, Ho Nyung Lee, George A. Sawatzky, Vladimir Hinkov,
// Valence-state reflectometry of complex oxide heterointerfaces//,
npj Quantum Materials volume 1, 16013 (2016) , arXiv, .

[75] Robert J. Green, Maurits W. Haverkort, G. A. Sawatzky,
Bond disproportionation and dynamical charge fluctuations in the perovskite rare-earth nickelates,
Physical Review B 94 (19), 195127 (2016) , arXiv, .

[74] A.A. Nugroho, Z. Hu, C.Y. Kuo, M.W. Haverkort, T.W. Pi, D. Onggo, M. Valldor, L.H. Tjeng,
// Cross-type orbital ordering in the layered hybrid organic-inorganic compound (C₆H₅CH₂CH₂NH₃)₂CuCl₄//,
Phys. Rev. B 94, 184404 (2016), arXiv, .

[73] S. Macke, J. E. Hamann-Borrero, R. J. Green, B. Keimer, G. A. Sawatzky, and M. W. Haverkort,
Dynamical Effects in Resonant X-Ray Diffraction,
Phys. Rev. Lett. 117, 115501 (2016), arXiv, .

[72] Y. Lu, A. Frano, M. Bluschke, M. Hepting, S. Macke, J. Strempfer, P. Wochner, G. Cristiani, G. Logvenov, H. U. Habermeier, M. W. Haverkort, B. Keimer, and E. Benckiser,
Quantitative determination of bond order and lattice distortions in nickel oxide heterostructures by resonant x-ray scattering,
Phys. Rev. B 93, 165121 (2016), arXiv, .

[71] C. Praetorius, M. Zinner, P. Hansmann, M. W. Haverkort, and K. Fauth,
Exploring small energy scales with x-ray absorption and dichroism,
Phys. Rev. B 93, 165107 (2016), arXiv, .

[70] Maurits W. Haverkort,
Quanty for core level spectroscopy - excitons, resonances and band excitations in time and frequency domain,
Journal of Physics: Conference Series 712, 012001 (2016), arXiv, .

[69] M. Hunault, V. Vercamer, Maurits W. Haverkort, Marie-Anne Arrio, C. Brouder, G. Calas, and A. Juhin,
Tracking the signature of low symmetry environments in the XAS Kpre-edge,
Journal of Physics: Conference Series 712, 012001 (2016), arXiv, .

2015

[68] Martin Sundermann, Fabio Strigari, Thomas Willers, Hannes Winkler, Andrey Prokofiev, James M. Ablett, Jean-Pascal Rue, Detlef Schmitz, Eugen Weschke, Marco Moretti Sala, Ali Al-Zein, Arata Tanaka, Maurits W. Haverkort, Deepa Kasinathan, Liu Hao Tjeng, Silke Paschen, and Andrea Severing,
CeRu₄Sn₆: a strongly correlated material with nontrivial topology,
Nature scientific reports 5, 17937 (2015), arXiv, .

[67] J.-P. Rueff, J. M. Ablett, F. Strigari, M. Deppe, M. W. Haverkort, L. H. Tjeng, and A. Severing,
Absence of orbital rotation in superconducting CeCu₂Ge₂,
Phys. Rev. B 91, 201108 (2015), arXiv, .

[66] D. Kasinathan, K. Koepernik, L. H. Tjeng, and M. W. Haverkort,
SmO thin films: A flexible route to correlated flat bands with nontrivial topology,
Phys. Rev. B 91, 195127 (2015), arXiv, [pdf] .

[65] S. Agrestini, Z. Hu, C.-Y. Kuo, M. W. Haverkort, K.-T. Ko, N. Hollmann, Q. Liu, E. Pellegrin, M. Valvidares, J. Herrero-Martin, P. Gargiani, P. Gegenwart, M. Schneider, S. Esser, A. Tanaka, A. C. Komarek, and L. H. Tjeng,
Electronic and spin states of SrRuO₃ thin films: An x-ray magnetic circular dichroism study,
Phys. Rev. B 91, 075127 (2015), arXiv, .

[64] F. Strigari, M. Sundermann, Y. Muro, K. Yutani, T. Takabatake, K.-D. Tsuei, Y. F. Liao, A. Tanaka, P. Thalmeier, M. W. Haverkort, L. H. Tjeng, and A. Severing,
Quantitative study of valence and configuration interaction parameters of the Kondo semiconductors CeM₂Al₁₀ (M = Ru, Os and Fe) by means of bulk-sensitive hard x-ray photoelectron spectroscopy,
J. Elec. Spec. Rel. Phen. 199, 56 (2015), arXiv, .

2014

[63] S. Macke, A. Radi, J. E. Hamann-Borrero, A. Verna, M. Bluschke, S. Brück, E. Goering, R. Sutarto, F. He, G. Cristiani, M. Wu, E. Benckiser, H.-U. Habermeier, G. Logvenov, N. Gauquelin, G. A. Botton, A. P. Kajdos, S. Stemmer, G. A. Sawatzky, M. W. Haverkort, B. Keimer, and V. Hinkov,
Element Specific Monolayer Depth Profiling,
Advanced Materials 26, 6545 (2014).

[62] M. W. Haverkort, G. Sangiovanni, P. Hansmann, A. Toschi, Y. Lu and S. Macke,
Bands, resonances, edge singularities and excitons in core level spectroscopy investigated within the dynamical mean-field theory,
Euro. Phys. Lett. 108 57004 (2014), arXiv, .

[61] Y. Lu, M. Höppner, O. Gunnarsson, and M. W. Haverkort,
Efficient real frequency solver for dynamical mean field theory,
Phys. Rev. B 90 085102 (2014), arXiv, .

[60] C. N. Veenstra, Z.-H. Zhu, M. Raichle, B. M. Ludbrook, A. Nicolaou, B. Slomski, G. Landolt, S. Kittaka, Y. Maeno, J. H. Dil, I. S. Elfimov, M. W. Haverkort, and A. Damascelli,
Spin-Orbital Entanglement and the Breakdown of Singlets and Triplets in Sr₂RuO₄ Revealed by Spin- and Angle-Resolved Photoemission Spectroscopy,
Phys. Rev. Lett. 112 127002 (2014), arXiv, .

[59] Z.-H. Zhu, C. N. Veenstra, S. Zhdanovich, M. P. Schneider, T. Okuda, K. Miyamoto, S.-Y. Zhu, H. Namatame, M. Taniguchi, M. W. Haverkort, I. S. Elfimov, and A. Damascelli,
Photoelectron Spin-Polarization Control in the Topological Insulator Bi₂Se₃,
Phys. Rev. Lett. 112 076802 (2014), arXiv, .

2013

[58] Krzysztof Wohlfeld, Satoshi Nishimoto, M. W. Haverkort, and Jeroen van den Brink,
Microscopic origin of spin-orbital separation in Sr₂CuO₃,
Phys. Rev. B 88 195138 (2013), arXiv,

[57] E. Benckiser, L. Fels, G. Ghiringhelli, M. Moretti Sala, T. Schmitt, J. Schlappa, V. N. Strocov, N. Mufti, G. R. Blake, A. A. Nugroho, T. T. M. Palstra, M. W. Haverkort, K. Wohlfeld, and M. Gruninger,
Orbital superexchange and crystal field simultaneously at play in YVO₃: Resonant inelastic x-ray scattering at the V L edge and the O K edge,
Phys. Rev. B 88 205115 (2013), arXiv, .

[56] A. Frano, E. Schierle, M. W. Haverkort, Y. Lu, M. Wu, S. Blanco-Canosa, U. Nwankwo, A. V. Boris, P. Wochner, G. Cristiani, H. U. Habermeier, G. Logvenov, V. Hinkov, E. Benckiser, E. Weschke, and B. Keimer,
Orbital Control of Noncollinear Magnetic Order in Nickel Oxide Heterostructures,
Phys. Rev. Lett. 111, 106804 (2013), arXiv, .

[55] M. Wu, E. Benckiser, M. W. Haverkort, A. Frano, Y. Lu, U. Nwankwo, S. Bruck, P. Audehm, E. Goering, S. Macke, V. Hinkov, P. Wochner, G. Christiani, S. Heinze, G. Logvenov, H.-U. Habermeier, and B. Keimer,
Strain and composition dependence of orbital polarization in nickel oxide superlattices,
Phys. Rev. B 88 125124 (2013), arXiv, .

[54] Z.-H. Zhu, C. N. Veenstra, G. Levy, A. Ubaldini, P. Syers, N. P. Butch, J. Paglione, M. W. Haverkort, I. S. Elfimov, and A. Damascelli,
Layer-by-layer entangled spin-orbital texture of the topological surface state in Bi₂Se₃,
Phys. Rev. Lett. 110, 216401 (2013), arXiv, .

[53] F. Strigari, T. Willers, Y. Muro, K. Yutani, T. Takabatake, Z. Hu, S. Agrestini, C.-Y. Kuo, Y.-Y. Chin, H.-J. Lin, T. W. Pi, C. T. Chen, E. Weschke, E. Schierle, A. Tanaka, M. W. Haverkort, L. H. Tjeng, and A. Severing,
Crystal field ground state of the orthorhombic Kondo semiconductors CeOs₂Al₁₀ and CeFe₂Al₁₀,
Phys. Rev. B 87 125119 (2013), arXiv, .

2012

[52] M. W. Haverkort, M. Zwierzycki, and O. K. Andersen,
Multiplet ligand-field theory using Wannier orbitals,
Phys. Rev. B 85 165113 (2012), arXiv, .

[51] T. Willers, F. Strigari, N. Hiraoka, Y. Q. Cai, M. W. Haverkort, K.-D. Tsuei, Y. F. Liao, S. Seiro, C. Geibel, F. Steglich, L. H. Tjeng, and A. Severing,
Determining the In-Plane Orientation of the Ground-State Orbital of CeCu₂Si₂,
Phys. Rev. Lett. 109, 046401 (2012), arXiv, .

[50] F. Strigari, T. Willers, Y. Muro, K. Yutani, T. Takabatake, Z. Hu, Y.-Y. Chin, S. Agrestini, H.-J. Lin, C. T. Chen, A. Tanaka, M. W. Haverkort, L. H. Tjeng, and A. Severing,
Crystal-field ground state of the orthorhombic Kondo insulator CeRu₂Al₁₀,
Phys. Rev. B 86 081105 (2012), arXiv, .

[49] M. A. Hossain, B. Bohnenbuck, Y. D. Chuang, M. W. Haverkort, I. S. Elfimov, A. Tanaka, A. G. Cruz Gonzalez, Z. Hu, H.-J. Lin, C. T. Chen, R. Mathieu, Y. Tokura, Y. Yoshida, L. H. Tjeng, Z. Hussain, B. Keimer, G. A. Sawatzky, and A. Damascelli,
Mott versus Slater-type metal-insulator transition in Mn-substituted Sr₃Ru₂O₇,
Phys. Rev. B 86 041102 (2012), arXiv, .

[48] S. Glawion, M. W. Haverkort, G. Berner, M. Hoinkis, G. Gavrilla, R. Kraus, M. Knopfer, M. Sing, and R. Claessen,
Unoccupied electronic structure of TiOCl studied using x-ray absorption near-edge spectroscopy,
J. Phys.: Condens. Matter 24, 255602 (2012), arXiv, .

[47] P. Hansmann, M. W. Haverkort, A. Toschi, G. Sangiovanni, F. Rodolakis, J. P. Rueff, M. Marsi, and K. Held,
Atomic and itinerant effects at the transition-metal x-ray absorption K pre-edge exemplified in the case of V₂O₃,
Phys. Rev. B 85 115136 (2012), arXiv, .

[46] J. Schlappa, K. Wohlfeld, K. J. Hou, M. Mourigal, M. W. Haverkort, V. N. Stocov, L. Hozoi, C. Monney, S. Nishimoto, S. Singh, A. Revcolevschi, J.-S. Caux, L. Patthey, H. M. Ronnow, J. van den Brink, and T. Schmitt,
Spin-Orbit Separation in the quasi 1D Mott-insulator Sr₂CuO₃,
Nature 485 82 (2012).

2011

[45] M. Le Tacon, G. Ghiringhelli, J. Chaloupka, M. Moretti Sala, V. Hinkov, M. W. Haverkort, M. Minola, M. Bakr, K. J. Zhou, S. Blanco-Canosa, C. Monney, Y. T. Song, G. L. Sun, C. T. Lin, G. M. De Luca, M. Salluzzo, G. Khaliullin, T. Schmitt, L. Braicovich, and B. Keimer,
Intense paramagnon excitations in a large family of high-temperature superconductors,
Nature Physics (2011), arXiv.

[44] E. Benckiser, M. W. Haverkort, S. Brück, E. Goering, S. Macke, A. Frañó, X. Yang, O. K. Andersen, G. Cristiani, H.-U. Habermeier, A. V. Boris, I. Zegkinoglou, P. Wochner, H.-J. Kim, V. Hinkov, and B. Keimer,
Orbital reflectometry of oxide heterostructures,
Nature Materials 10, 189 (2011), arXiv.

[43] S. Glawion, J. Heidler, M. W. Haverkort, L. C. Duda, T. Schmitt, V. N. Strocov, C. Monney, K. J. Zhou, A. Ruff, M. Sing, and R. Claessen,
Two-Spinon and Orbital Excitations of the Spin-Peierls System TiOCl,
Phys. Rev. Lett. 107, 107402 (2011), arXiv, .

[42] N. Hiraoka, M. Suzuki, K. D. Tsuei, H. Ishii, Y. Q. Cai, M. W. Haverkort, C. C. Lee and W. Ku,
dd excitations in three-dimensional q-space: A nonresonant inelastic X-ray scattering study on NiO,
Europhys. Lett. 96, 37007 (2011), arXiv, .

[41] Subhra Sen Gupta, J. A. Bradley, M. W. Haverkort, G. T. Seidler, A. Tanaka, G. A. Sawatzky,
Coexistence of bound and virtual bound states in shallow-core to valence x-ray spectroscopies,
Phys. Rev. B 84 075134 (2011), arXiv, .

[40] F. Rodolakis, J.-P. Rueff, M. Sikora, I. Alliot, J.-P. Itie, F. Baudelet, S. Ravy, P. Wzietek, P. Hansmann, A. Toschi, M. W. Haverkort, G. Sangiovanni, K. Held, P. Metcalf, and M. Marsi,
Evolution of the electronic structure of a Mott system across its phase diagram: X-ray absorption spectroscopy study of (V_1-xCr_x)₂O₃,
Phys. Rev. B 84, 245113 (2011), arXiv, .

[39] N. Hollmann, M. W. Haverkort, M. Benomar, M. Cwik, M. Braden, and T. Lorenz,
Evidence for a temperature-induced spin-state transition of Co3+ in La_2-xSr_xCoO₄,
Phys. Rev. B 83, 174435 (2011), arXiv, .

2010

[38] M. W. Haverkort,
Theory of Resonant Inelastic X-Ray Scattering by Collective Magnetic Excitations,
Phys. Rev. Lett. 105, 167404 (2010), arXiv, .

[37] F. Rodolakis, P. Hansmann, J.-P. Rueff, A. Toschi, M. W. Haverkort, G. Sangiovanni, A. Tanaka, T. Saha-Dasgupta, O. K. Andersen, K. Held, M. Sikora, I. Alliot, J.-P. Itié, F. Baudelet, P. Wzietek, P. Metcalf, and M. Marsi,
Inequivalent Routes across the Mott Transition in V₂O₃ Explored by X-Ray Absorption,
Phys. Rev. Lett. 104, 047401 (2010), arXiv, .

[36] O. Gunnarsson, G. Sangiovanni, A. Valli, and M. W. Haverkort,
Fourier transformation and response functions,
Phys. Rev. B 82, 233104 (2010), arXiv, .

[35] G. M. De Luca, G. Ghiringhelli, M. Moretti Sala, S. Di Matteo, M. W. Haverkort, H. Berger, V. Bisogni, J. C. Cezar, N. B. Brookes, and M. Salluzzo,
Weak magnetism in insulating and superconducting cuprates,
Phys. Rev. B 82, 214504 (2010), arXiv, .

[34] O. Gunnarsson, M. W. Haverkort, and G. Sangiovanni,
Analytical continuation of imaginary axis data for optical conductivity,
Phys. Rev. B 82, 165125 (2010), arXiv, .

[33] O. Gunnarsson, M. W. Haverkort, and G. Sangiovanni,
Analytical continuation of imaginary axis data using maximum entropy,
Phys. Rev. B 81, 155107 (2010), arXiv, .

[32] M. W. Haverkort, N. Hollmann, I. P. Krug, and A. Tanaka,
Symmetry analysis of magneto-optical effects: The case of x-ray diffraction and x-ray absorption at the transition metal L_2,3 edge,
Phys. Rev. B 82, 094403 (2010), arXiv, .

[31] T. Haupricht, R. Sutarto, M. W. Haverkort, H. Ott, A. Tanaka, H. H. Hsieh, H.-J. Lin, C. T. Chen, Z. Hu, and L. H. Tjeng,
Local electronic structure of Fe²⁺ impurities in MgO thin films: Temperature-dependent soft x-ray absorption spectroscopy study,
Phys. Rev. B 82, 035120 (2010), arXiv, .

[30] J. A. Bradley, S. Sen Gupta, G. T. Seidler, K. T. Moore, M. W. Haverkort, G. A. Sawatzky, S. D. Conradson, D. L. Clark, S. A. Kozimor, and K. S. Boland,
Probing electronic correlations in actinide materials using multipolar transitions,
Phys. Rev. B 81, 193104 (2010), arXiv, .

2009

[29] S. Altieri, M. Finazzi, H. H. Hsieh, M. W. Haverkort, H.-J. Lin, C. T. Chen, S. Frabboni, G. C. Gazzadi, A. Rota, S. Valeri, and L. H. Tjeng,
Image charge screening: A new approach to enhance magnetic ordering temperatures in ultrathin correlated oxide films,
Phys. Rev. B 79, 174431 (2009), arXiv, .

[28] R. A. Gordon, M. W. Haverkort, Subhra Sen Gupta and G. A. Sawatzky,
Orientation-dependent x-ray Raman scattering from cubic crystals: Natural linear dichroism in MnO and CeO₂,
J. Phys.: Conf. Ser. 190 012047 (2009), .

[27] F. Rodolakis, P. Hansmann, J.-P. Rueff, A. Toschi, M. W. Haverkort, G. Sangiovanni, K. Held, M. Sikora, A. Congeduti, J-P. Itié, F. Baudelet, P. Metcalf and M. Marsi,
Electronic correlations in V₂O₃ studied with K-edge X-ray absorption spectroscopy,
J. Phys.: Conf. Ser. 190 012092 (2009), .

2008

[26] M. W. Haverkort, I. S. Elfimov, L. H. Tjeng, G. A. Sawatzky, and A. Damascelli,
Strong Spin-Orbit Coupling Effects on the Fermi Surface of Sr₂RuO₄ and Sr₂RhO₄,
Phys. Rev. Lett. 101, 026406 (2008), arXiv, .

[25] M. A. Hossain, Z. Hu, M. W. Haverkort, T. Burnus, C. F. Chang, S. Klein, J. D. Denlinger, H.-J. Lin, C. T. Chen, R. Mathieu, Y. Kaneko, Y. Tokura, S. Satow, Y. Yoshida, H. Takagi, A. Tanaka, I. S. Efimov, G. A. Sawatzky, L. H. Tjeng, and A. Damascelli,
Crystal-Field Level Inversion in Lightly Mn-Doped Sr₃Ru₂O₇,
Phys. Rev. Lett. 101, 016404 (2008), arXiv, .

[24] P. Hansmann, A. Severing, Z. Hu, M. W. Haverkort, C. F. Chang, S. Klein, A. Tanaka, H. H. Hsieh, H.-J. Lin, C. T. Chen, B. Fåk, P. Lejay, and L. H. Tjeng,
Determining the Crystal-Field Ground State in Rare Earth Heavy Fermion Materials Using Soft-X-Ray Absorption Spectroscopy,
Phys. Rev. Lett. 100, 066405 (2008), arXiv, .

[23] J. Schlappa, C. Schüßler-Langeheine, C. F. Chang, H. Ott, A. Tanaka, Z. Hu, M. W. Haverkort, E. Schierle, E. Weschke, G. Kaindl, and L. H. Tjeng,
Direct Observation of t_2g Orbital Ordering in Magnetite,
Phys. Rev. Lett. 100, 026406 (2008), arXiv, .

[22] I. P. Krug, F. U. Hillebrecht, H. Gomonaj, M. W. Haverkort, A. Tanaka, L. H. Tjeng and C. M. Schneider,
Magnetic coupling in highly ordered NiO/Fe₃O₄ (110): Ultrasharp magnetic interfaces v.s. long-range magnetoelastic interactions,
Europhys. Lett. 81 17005 (2008), arXiv, .

[21] R. A. Gordon, G. T. Seidler, T. T. Fister, M. W. Haverkort, G. A. Sawatzky, A. Tanaka and T. K. Sham,
High multipole transitions in NIXS: Valence and hybridization in 4f systems,
Europhys. Lett. 81 26004 (2008), arXiv, .

[20] N. Hollmann, M. W. Haverkort, M. Cwik, M. Benomar, M. Reuther, A. Tanaka and T. Lorenz,
Anisotropic susceptibility of La_2-xSr_xCoO₄ related to the spin states of cobalt,
New J. Phys. 10 023018 (2008), arXiv, .

[19] Michel van Veenendaal and M. W. Haverkort,
Effective operator for d-d transitions in nonresonant inelastic x-ray scattering,
Phys. Rev. B 77, 224107 (2008), arXiv, .

[18] T. Burnus, Z. Hu, H. H. Hsieh, V. L. J. Joly, P. A. Joy, M. W. Haverkort, Hua Wu, A. Tanaka, H.-J. Lin, C. T. Chen, and L. H. Tjeng,
Local electronic structure and magnetic properties of LaMn0.5Co0.5O3 studied by x-ray absorption and magnetic circular dichroism spectroscopy,
Phys. Rev. B 77, 125124 (2008), arXiv, .

[17] A. Gössling, M. W. Haverkort, M. Benomar, Hua Wu, D. Senff, T. Möller, M. Braden, J. A. Mydosh, and M. Grüninger,
Mott-Hubbard versus charge-transfer behavior in LaSrMnO⁴ studied via optical conductivity,
Phys. Rev. B 77, 035109 (2008), arXiv, .

[16] A. Gössling, R. Schmitz, H. Roth, M. W. Haverkort, T. Lorenz, J. A. Mydosh, E. Müller-Hartmann, and M. Grüninger,
Mott-Hubbard exciton in the optical conductivity of YTiO3 and SmTiO3,
Phys. Rev. B 78, 075122 (2008), arXiv, .

[15] I. P. Krug, F. U. Hillebrecht, M. W. Haverkort, A. Tanaka, L. H. Tjeng, H. Gomonay, A. Fraile-Rodríguez, F. Nolting, S. Cramm, and C. M. Schneider,
Impact of interface orientation on magnetic coupling in highly ordered systems: A case study of the low-indexed Fe₃O₄/NiO interfaces,
Phys. Rev. B 78, 064427 (2008), .

2007

[14] M. W. Haverkort, A. Tanaka, L. H. Tjeng, and G. A. Sawatzky,
Nonresonant Inelastic X-Ray Scattering Involving Excitonic Excitations: The Examples of NiO and CoO,
Phys. Rev. Lett. 99, 257401 (2007), arXiv, .

2006

[13] A. Podlesnyak, S. Streule, J. Mesot, M. Medarde, E. Pomjakushina, K. Conder, A. Tanaka, M. W. Haverkort, and D. I. Khomskii,
Spin-State Transition in LaCoO₃: Direct Neutron Spectroscopic Evidence of Excited Magnetic States,
Phys. Rev. Lett. 97, 247208 (2006), arXiv, .

[12] M. W. Haverkort, Z. Hu, J. C. Cezar, T. Burnus, H. Hartmann, M. Reuther, C. Zobel, T. Lorenz, A. Tanaka, N. B. Brookes, H. H. Hsieh, H.-J. Lin, C. T. Chen, and L. H. Tjeng,
Spin State Transition in LaCoO₃ Studied Using Soft X-ray Absorption Spectroscopy and Magnetic Circular Dichroism,
Phys. Rev. Lett. 97, 176405 (2006), arXiv, .

[11] T. C. Koethe, Z. Hu, M. W. Haverkort, C. Schüßler-Langeheine, F. Venturini, N. B. Brookes, O. Tjernberg, W. Reichelt, H. H. Hsieh, H.-J. Lin, C. T. Chen, and L. H. Tjeng,
Transfer of Spectral Weight and Symmetry across the Metal-Insulator Transition in VO2,
Phys. Rev. Lett. 97, 116402 (2006), .

[10] T. Burnus, Z. Hu, M. W. Haverkort, J. C. Cezar, D. Flahaut, V. Hardy, A. Maignan, N. B. Brookes, A. Tanaka, H.-H. Hsieh, H.-J. Lin, C.-T. Chen, and L. H. Tjeng,
Valence, spin, and orbital state of Co ions in one-dimensional Ca₃Co₂O₆: An x-ray absorption and magnetic circular dichroism study,
Phys. Rev. B 74, 245111 (2006), arXiv, .

2005

[9] M. W. Haverkort, Z. Hu, A. Tanaka, W. Reichelt, S. V. Streltsov, M. A. Korotin, V. I. Anisimov, H. H. Hsieh, H.-J. Lin, C. T. Chen, D. I. Khomskii, and L. H. Tjeng,
Orbital-assisted metal-insulator transition in VO₂,
Phys. Rev. Lett. 95, 196404 (2005), arXiv, .

[8] Hua Wu, M. W. Haverkort, Z. Hu, D. I. Khomskii, and L. H. Tjeng,
Nature of magnetism in Ca₃Co₂O₆,
Phys. Rev. Lett. 95, 186401 (2005), arXiv, .

[7] S. I. Csiszar, M. W. Haverkort, Z. Hu, A. Tanaka, H. H. Hsieh, H.-J. Lin, C. T. Chen, T. Hibma, and L. H. Tjeng,
Controlling Orbital Moment and Spin Orientation in CoO Layers by Strain,
Phys. Rev. Lett. 95, 187205 (2005), arXiv, .

[6] R. Rückamp, J. Baier, M. Kriener, M. W. Haverkort, T. Lorenz, G. S. Uhrig, L. Jongen, A. Möller, G. Meyer, and M. Grüninger,
Zero-Field Incommensurate Spin-Peierls Phase with Interchain Frustration in TiOCl,
Phys. Rev. Lett. 95, 097203 (2005), arXiv, .

[5] M. W. Haverkort, Z. Hu, A. Tanaka, G. Ghiringhelli, H. Roth, M. Cwik, T. Lorenz, C. Schüßler-Langeheine, S. V. Streltsov, A. S. Mylnikova, V. I. Anisimov, C. de Nadai, N. B. Brookes, H. H. Hsieh, H.-J. Lin, C. T. Chen, T. Mizokawa, Y. Taguchi, Y. Tokura, D. I. Khomskii, and L. H. Tjeng,
Determination of the Orbital Moment and Crystal-Field Splitting in LaTiO₃,
Phys. Rev. Lett. 94, 056401 (2005), arXiv, .

[4] R. Rückamp, E. Benckiser, M. W. Haverkort, H. Roth, T. Lorenz, A. Freimuth, L. Jongen, A. Möller, G. Meyer, P. Reutler, B. Büchner, A. Revcolevschi, S.-W. Cheong, C. Sekar, G. Krabbes, and M. Grüninger,
Optical study of orbital excitations in transition-metal oxides,
New Journal of Physics 7, 144 (2005), .

2004

[3] Z. Hu, Hua Wu, M. W. Haverkort, H. H. Hsieh, H.-J. Lin, T. Lorenz, J. Baier, A. Reichl, I. Bonn, C. Felser, A. Tanaka, C. T. Chen, and L. H. Tjeng,
Different Look at the Spin State of Co³⁺ Ions in a CoO₅ Pyramidal Coordination,
Phys. Rev. Lett. 92, 207402 (2004), arXiv, .

[2] A. D. Rata, A. R. Chezan, T. Hibma, M. W. Haverkort, L. H. Tjeng, H. H. Hsieh, H.-J. Lin, and C. T. Chen,
// Growth and properties of strained VOx thin films with controlled stoichiometry//,
Phys. Rev. B 69, 075404 (2004), arXiv, .

[1] M. W. Haverkort, S. I. Csiszar, Z. Hu, S. Altieri, A. Tanaka, H. H. Hsieh, H.-J. Lin, C. T. Chen, T. Hibma, and L. H. Tjeng,
// Magnetic versus crystal field linear dichroism in NiO thin films//,
Phys. Rev. B 69, 020408(R) (2004), arXiv, .

Invited contributions

M. W. Haverkort and O. K. Andersen,
Multiplet ligand-field theory using Wannier orbitals,
Internal Annual Report of the MPI-FKF Stuttgart 2011, (2012), .

M. Le Tacon, J. Chaloupka, M. W. Haverkort, V. Hinkov, S. Blanco-Canosa, M. Bakr, G. L. Sun, Y. T. Song, C. T. Lin, G. Khaliullin, and B. Keimer,
Intense paramagnon excitations in a large family of high-temperature superconductors,
Internal Annual Report of the MPI-FKF Stuttgart 2011, (2012), .

O. Gunnarsson, M. W. Haverkort and G. Sangiovanni,
Analytical continuation of imaginary axis data using maximum entropy,
Internal Annual Report of the MPI-FKF Stuttgart 2010, (2011), .

E. Benckiser, M. W. Haverkort, A. Frañó, O. K. Andersen, G. Cristiani, H.-U. Habermeier, A. V. Boris, I. Zegkinoglou, V. Hinkov and B. Keimer,
Orbital reflectometry of oxide heterostructures,
Internal Annual Report of the MPI-FKF Stuttgart 2010, (2011), .

M. W. Haverkort,
Theory of resonant inelastic X-ray scattering by collective magnetic excitations,\\Internal Annual Report of the MPI-FKF Stuttgart 2009, (2010), .

G.-Q. Liu, V. N. Antonov, M. W. Haverkort, O. Jepsen, and O. K. Andersen,
Coulumb-enhanced spin-orbit splitting: The missing piece in the Sr₂RhO₄ puzzle,
Internal Annual Report of the MPI-FKF Stuttgart 2008, (2009), .

J. Schlappa, C. Schüßler-Langeheine, C. F. Chang, H. Ott, A. Tanaka, Z. Hu, M. W. Haverkort, E. Schierle, E. Weschke, G. Kaindl and L. H. Tjeng,
Cool magnetite: Frozen electrons below the Verwey temperature,
BESSY Highlights 2007, (2008), .

M. W. Haverkort, Z. Hu, J. C. Cezar, T. Burnus, H. Hartmann, M. Reuther, C. Zobel, T. Lorenz, A. Tanaka, N. B. Brookes, H. H. Hsieh, H.-J. Lin, C. T. Chen and L. H. Tjeng,
Spin state transition in LaCoO₃ studied using soft X-ray absorption spectroscopy and magneic circular dichrosim,
ESRF Highlights 2006 - X-Ray Absorption and Magnetic Scattering, (2007), .

M. W. Haverkort, Z. Hu, A. Tanaka, H. H. Hsieh, H.-J. Lin, C. T. Chen and L. H. Tjeng,
The Spin State Transition In LaCoO₃; Revising A Revision,
NSRRC Activety Report - Research Highlights - Material Physics, (2007), .

M. W. Haverkort, Z. Hu, S. I. Csiszar, T. Hibma, A. Tanaka, H. H. Hsieh, H.-J. Lin, C. T. Chen and L. H. Tjeng,
Controlling Orbital Moment and Spin Orientation in CoO Layers by Strain,
NSRRC Activety Report - Research Highlights - Material Physics, (2006), .

M. W. Haverkort, Z. Hu, A. Tanaka, H. H. Hsieh, H.-J. Lin, C. T. Chen and L. H. Tjeng,
Orbital-Assisted Metal-Insulator Transition in VO₂,
NSRRC Activety Report - Research Highlights - Material Physics, (2006), .

M. W. Haverkort, Z. Hu, H. H. Hsieh, H.-J. Lin, C. T. Chen and L. H. Tjeng,
Determination of the Crystal Field Splitting and the Orbital Moment in LaTiO₃,
NSRRC Activety Report - Research Highlights - Material Physics, (2005), .

PhD. Thesis

M. W. Haverkort
Spin and orbital degrees of freedom in transition metal oxides and oxide thin films studied by soft x-ray absorption spectroscopy,
PhD. Thesis, University of Cologne, June 2005, arXiv, .