Photoelectron spectroscopy at DESY

Gitanjali Kolhatkar is studying the fundamental mechanisms of ferroelectric materials. Alena Nierhauve is working with self-developed instruments on photoelectron spectroscopy at DESY (Deutsches Elektronen-Synchrotron). Together they discussed how to optimize the material composition with the help of ASPHERE III" - an angle-, spin-, and position-resolving photoelectron spectrometer at DESY.

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Dr. Gitanjali Kolhatkar

Group of Nanoelectronics

I am working on materials that display a spontaneous electric polarization which can be switched by applying an external electric field. These so called ferroelectric materials are candidates for novel non-volatile memory devices, micro- sensors, or optical modulators. In our experiments we study the fundamental mechanisms and try to optimize the operation parameters as well as the material composition of real devices that are fabricated in our labs in Kiel. Photoelectron spectroscopy at DESY gives us insight into the local chemical composition upon polarization switching and during device operation that can hardly be studied with other methods, particularly since the ferroelectric material is buried under a thin electrode. It is great that we have those research capabilities near to Kiel and the support of partners like Alena.

Alena Nierhauve

Group of Solid State Research with Synchrotron Radiation

Our group has many years of experience with photoelectron spectroscopy and the development of own instruments at DESY. If someone is interested in scientific experiments and a cooperation with us, we discuss the respective scientific questions and the technical feasibility such that they can write a beamtime application, which is reviewed by an external panel. During the experiments, it was very advantageous for our cooperation partners to have an experienced experimenter around who  could help to optimize the parameters and to discuss the results. On the other hand, for myself as a doctoral researcher within the CRC 1461 “Neurotronics: Bio-inspired Information Pathways“, where I am working on memristic devices, a cooperation with scientists of a similar field is particularly interesting and fosters a rewarding exchange between our groups.


ASPHERE III is an angle-, spin-, and positionresolving photoelectron spectrometer at DESY. It is capable of determining complete threedimensional band structures and Fermi surfaces at a spatial resolution of below 10 x 10 μm2. All spectroscopic investigations can be performed in-situ and in-operando during sample temperature changes, the application of voltages, or the deposition of alkali or transition metals on sample surfaces.


Variable-polarization soft X-ray beamline P04 of PETRA III at DESY (Deutsches Elektronen-Synchrotron), in Hamburg


Prof. Dr. Kai Rossnagel, Group of Solid State Research with Synchrotron Radiation and Ruprecht-Haensel-Laboratory

Sample preparation:
  • Molecular beam epitaxy (MBE)
  • Ar sputtering
  • Annealing
  • E-beam evaporation
  • Alkali metal deposition

Experimental Methods:
  • XPS
  • Spin-(AR)PES
  • Space-resolved ARPES
  • XMCD
  • XPD
  • LEED