Regensburg 2010 – scientific programme

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MA: Fachverband Magnetismus

MA 33: Poster II

MA 33.44: Poster

Friday, March 26, 2010, 11:00–14:00, Poster B1

Advanced imaging and characterization of ferroic domains by optical second harmonic generation — Christian Wehrenfennig, •Dennis Meier, and Manfred Fiebig — Helmholtz-Institut für Strahlen- und Kernphysik, Nußallee 14-16, 53115 Bonn

In the investigation of magnetic and electric order in solid state systems, understanding the domain topologies is of prime significance, especially because it directly influences the performance in technical applications. The behavior of domains and domain walls reveals valuable information about the microscopic interactions and interaction paths leading to magnetic and electric ordering and, in particular, magnetoelectric couplings in multiferroics. With optical second harmonic generation (SHG), a powerful technique exists for probing all types of ferroic order using the same experimental setup. Most notably, it enables straightforward imaging even of antiferroic domains.

Here we present two advanced possibilities of domain characterization by SHG: (1) In antiferromagnetic compounds with incommensurate periodical modulation of the magnetic moment, conventional techniques fail to distinguish between adjacent translation domains, since they do not differ in the orientation of the order parameter. In contrast, SHG allows us to image those domains by phase sensitive detection. (2) Optical visualization of very small domains is naturally restricted by the resolution limit. Here we present a statistical model, which allows us to exploit the information in the remaining signal to estimate the average size of domains, even if it is orders of magnitude below the resolution limit.