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Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 58: Multiferroics II (organized by MA)

TT 58.12: Talk

Wednesday, April 2, 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)

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