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MA: Fachverband Magnetismus

MA 38: Multiferroics

MA 38.11: Vortrag

Donnerstag, 26. März 2009, 18:00–18:15, HSZ 103

Analysis of ferroelectric and magnetic chiral order in MnWO₄ — •Naëmi Leo¹, Dennis Meier¹, Thomas Lottermoser¹, Michael Maringer¹, Petra Becker², Ladislav Bohatý², and Manfred Fiebig¹ — ¹HISKP, Universität Bonn — ²Institut für Kristallographie, Universität zu Köln

Spin spiral systems form a particularly interesting subgroup of magnetoelectric multiferroics since violation of inversion symmetry by long-wavelength magnetic order is responsible for the spontaneous electric polarisation. Such intrinsic coupling of magnetism and ferroelectricity is not only promising with respect to future spintronic applications. It also enables fascinating physical effects like the magnetic-field-induced polarisation flop in TbMnO₃ or MnWO₄.

In our studies we focus on MnWO₄, which is a remarkable example of a spin-spiral multiferroic because a single transition-metal ion is responsible for the coexistence of magnetic and electric order. We present a spectral analysis of its multiferroic phase by means of optical second harmonic generation (SHG). With respect to symmetry dependent selection rules we distinguish between crystallographic, antiferromagnetic (AFM) and ferroelectric (FE) SHG contributions of different multipole order. Characteristic temperature dependencies of the associated FE and AFM order parameters further support the attribution. This work is supported by the DFG through SFB 608.