Dipl.-Phys. Sascha Albert Bräuninger



Dipl.-Phys. Sascha Albert Bräuninger
Technische Universität Dresden
Institut für Festkörperphysik
Zellescher Weg 16, Raum D 209
01069 Dresden

Tel.: +49 351 463-42120
Fax: +49 351 463-37734

Supported by the SFB 1143.


Research Interests

The research focus is the nuclear probe investigation of geometrically frustrated materials with exotic ground states and phase transitions. In this magnetic materials the total energy cannot be minimized by minimizing the exchange interaction between all spin pairs simultaneously. A structure example consisting of edge-sharing tetrahedra is given by the SFB 1143 logo above, the so called pyrochlores. The edges are antiferromagnetically coupled spins. The experimental properties of such kind of lattices generated by frustrated substructures are highly degenerate ground states, thus a zero temperature residual entropy and especially a suppression of magnetic long-range order is observed. The consequences are fascinating und unexpected ground states and phases depending on the conditions of the lattice, the electronic strctures and perturbations:

  • spin glass (Y2Mo2O7,Tb2Mo2O7)
  • spin liquid (Tb2Ti2O7,Yb2Ti2O7)
  • disordered spin ice in which magnetic dipoles fractionalized in monopoles (Ho2Ti2O7,Dy2Ti2O7)
  • ordered spin ice (Tb2Sn2O7)
  • effects like order-by-disorder (Er2Ti2O7)

to give selected examples for pyrochlore oxides. Nowadays frustration is one of the most important research fields in magnetism and solid matter physics due to the exotic low temperature behavior and there are still a lot of open questions. For the interested student:

Geometrical Frustration: Moessner and Ramirez, Physics Today, 2006

Spin liquids in frustrated magnets, Balents, Nature 464, 199-208, 2010

Our investigation techniques are using a nuclear particle as a probe (e.g. the nucleus or a muon µ+):

These spectroscopy methods enable us to distinguish between different magnetic phases, to identify phase transitions in detail and to classify undiscovered states.

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Letzte Änderung: 27.05.2016