Resonant soft x-ray scattering studies of electronic orders in transition metal oxides and related heterostructures.

• Applicant: Dr. Jorge-Enrique Hamann Borrero
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2012 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 213948008

• Final Report Year: 2018

Final Report Abstract

The major contribution from the concluding proposal has been to bring the resonant x-ray reflectivity technique to a mature stage where it can be widely used to study magnetic and electronic properties of heterointerfaces. During this project we have enhanced the capabilities of the technique to study not only structural information with monolayer precision, but also to extract highly valuable electronic properties as valence states and local electronic anisotropies with dept- and site-resolution, all this being non-destructive. We have provided a new methodology, from experiment design, until data modeling and analysis, so that such information can be obtained. With all this, the grantee and his team of collaborators have developed RXR so that is has become a unique and powerful method to study electronic properties of surface and buried interfaces of complex materials. The next step is to implement the method on relevant systems where interesting novel phenomena takes place at surfaces and interfaces. For instance, study of topological surface states on bulk materials, surface spin currents in Spin-Hall effect devices, diverse proximity effects at interfaces, skyrmion lattices at interfaces, among others. Furthermore, a natural next step is the study of transient states and their dynamics by means of pump probe experiments using RXR. In this way on can learn, for example, about evolution and dynamics of magnetization upon optical pumping in thin films with depth- and time-resolution. In this regard, the grantee in putting special efforts to further develop RXR with time resolution using x-ray free electron lasers. Thus, for RXR, the future is bright.

Publications

• “Electronic depth profiles with atomic layer resolution from resonant soft x-ray reflectivity”, New Journal of Physics, 17, 083046 (2015)
  M. Zwiebler, J. E. Hamann-Borrero, M. Vafaee, P. Komissinskiy, S. Macke, R. Sutarto, F. He, B. Buchner, G. A. Sawatzky, L. Alff and J. Geck
  
• “Dynamical Effects in Resonant X-Ray Diffraction”, Phys. Rev. Lett. 117, 115501 (2016)
  S. Macke, J. E. Hamann-Borrero, R. J. Green, B. Keimer, G. A. Sawatzky, and M. W. Haverkort
  
• “Valence-state reflectometry of complex oxide heterointerfaces” , Npj Quantum Materials, 1, 16013 (2016)
  J.E. Hamann-Borrero, S. Macke, W. S. Choi, R. Sutarto, F. He, A. Radi, A.I. Elfimov, R. J. Green, M. W. Haverkort, V. B. Zabolotnyy, H. N. Lee, G. A. Sawatzky and V. Hinkov
  
• “Chemical vapor transport and characterization of MnBi2 Se4 ”, Journal of Crystal Growth 459, 81 (2017)
  C. Nowka, M. Gellesch, J. E. Hamann- Borrero, S. Partzsch, C. Wuttke, F. Steckel, C. Hess, A.U.B. Wolter, L. T. Corredor-Bohorquez, B. Buchner and S. Hampel
  
• “Site-selective spectroscopy with depth resolution using resonant x-ray reflectometry”, Scientific Reports 7, 13792 (2017)
  J. E. Hamann- Borrero, S. Macke, B. Gray, M. Kareev, E. Schierle, S. Partzsch, M. Zwiebler, U. Treske, A. Koitzsch, B. Buchner, J. W. Freeland, J. Chakhalian and J. Geck
  
• “Observation of heavy spin-orbit excitons propagating in a nonmagnetic background: The case of (Ba,Sr)2 YIrO6 ” , Phys. Rev. B 97, 064421 (2018)
  M. Kusch, V. M. Katukuri, N. A. Bogdanov, B. Buchner, T. Dey, D. V. Efremov, J. E. Hamann-Borrero, B. H. Kim, M. Krisch, A. Maljuk, M. Moretti Sala, S. Wurmehl, G. Aslan- Cansever, M. Sturza, L. Hozoi, J. van den Brink, and J. Geck