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TT: Fachverband Tiefe Temperaturen

TT 58: Multiferroics II (organized by MA)

TT 58.12: Vortrag

Mittwoch, 2. April 2014, 12:30–12:45, HSZ 04

Magnetic properties of multiferroic TbMnO₃ — •Natalya Fedorova, Andrea Scaramucci, Claude Ederer, and Nicola Spaldin — ETH Zurich, Materials Theory, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich, Switzerland

We use ab-initio calculations to investigate the magnetic properties of multiferroic TbMnO₃.

At low temperatures TbMnO₃ demonstrates an incommensurate spiral ordering of Mn spins which is accompanied by appearance of spontaneous electric polarization driven by applied magnetic field [1]. The establishment of such spin ordering is usually described within the framework of a Heisenberg model with competing nearest-neighbor and next-nearest-neighbor exchange interactions. However, our theoretical estimations of these interactions by ab-initio calculations demonstrate a clear deviation from Heisenberg model.

We consider first the coupling between magnetic and orbital orderings as a main source of non-Heisenberg behavior in TbMnO₃, but conclude that it does not explain the observed deviation. We find that higher order interactions (biquadratic and four-body spin couplings) should be taken into account for proper treatment of the magnetism in TbMnO₃.

[1] T. Kimura et al., Nature 426, 55-58 (2003)