Contact

Prof. Dr. Markus Münzenberg
Institut für Physik

Felix-Hausdorff-Str. 6
17489 Greifswald

Telefon +49 3834 420-4780
Telefax: +49 3834 420-4701
markus.muenzenberg(at)uni-greifswald(dot)de

What are the limits to control ultrafast dynamics? With our research we want to unify concepts from femtosecond spin dynamics and spintransport on the nanoscale to make use of them in novel spintronic devices ...

Leading to understanding of microscopic processes and novel applications. 

Research

  • Ultrafast Magnetism and THz Spintronics
  • Magnonics and Spincaloritronics
  • Topological Insulators
  • Mechanics of Bionanosystems

Details on our reserach more...


Picosecond spin currents as THz source

Terahertz waves offer numerous applications in ultrafast science. A a new concept for the generation of terahertz waves using spintronic materials can be realized.
In contrast to previous designs, the emitters consist of thin metal films and take advantage of the spin rather than only the charge of the electron. Following this approach, they developed broadband emitters fully covering the 1-to-30-THz range, while at the same time being simple designed and compact. Compact, because it is based on spin-orbit effects on femtosecond time scales converting the spin current into a THz emitting charge current on few nanometer lenght scales. 
Original article: 
T. Seifert et al., Efficient metallic spintronic emitters of ultrabroadband terahertz radiation, Nature Photonics 10, 483–488 (2016).

Nature Photonics

Coherent ultrafast spin-dynamics probed in three dimensional topological insulators

What happens if a Topological Insulator is driven with circularly polarized photons? A Topological Insulator is not a magnetic material, but due to its topological properties spin-currents are connected with their surface states. In our research we could identify the origin of a recently seen coherent spin-signal present at the ultrafast time scale in these materials. It originates from a coherent spin-polarization present at ultrafast time scales … 


Original article:
Coherent ultrafast spin-dynamics probed in three dimensional topological insulators, F. Boschini et al. Scientific Reports 5, 15304 (2015).

Scientific Reports

All-optical spin manipulation:

Magnetisation switching of FePt nanoparticle recording medium by femtosecond laser pulses

In a collaboration between Universities of Uppsala, Konstanz, Kiel, Madrid and Western Digital, we lifted the mystery of all-optical manipulation of the magnetization of FePt recording media. Today, FePt nanograins are developed, because of their large magnetic anisotropy, resulting in a high thermal stability even for a few nanometer sized grains, arising in their high coercive field of more than 4 Tesla. They are currently developed further for heat assisted magnetic recording. Our collaboration showed that different steps are important, from ab-initio calculations of the light induced magnetization up to the correct thermal description of the spin ensemble. That shows again the complexity of ultrafast magnetization dynamics, and that there is no unique process for describing ultrafast magnetism. Our calculations for each grain entered into a simple rate model that can explain the switching statistics. To date multiple laser pulses are needed to get a decent writing success. With our single shot experiments compared to the calculations, we can make now predictions for the boundary condition for single-shot laser writing of magnetic bits in the future.  

Reference:

Magnetisation switching of FePt nanoparticle recording medium by femtosecond laser pulses

R. John, M. Berritta, D. Hinzke, C. Müller, T. Santos, H. Ulrichs, P. Nieves, J. Walowski, R. Mondal, O. Chubykalo-Fesenko, J. McCord, P. M. Oppeneer, U. Nowak, M. Münzenberg, Sci. Rep. 7, 4114 (2017). 

Online publication date: 23-Jun-2017.

Wieck drawbridge in nano:

Smallest elements are 800 nm in size. Our laserlithography allows highest resolution 3D writing by two-photon processes (Denker/Medvedev).

New equipment allows to fabricate three dimensional objects with a resolution of 150nm. As a test object we fabricated the dutch style drawbridge in the fisher village Wieck, a Greifswald local landmark (original on Wiki). The process works with pulsed laser writing by two-photon laser polymerization that allows to shrink the volume of writing a photoresist for pattering nano- and micron sized structures.

On TV, watch the contribution at the NDR news magazinewww.ndr.de