Berlin 2012 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 10: Multiferroics II: Hexagonal manganites / Incommensurate multiferroics (jointly with MA, DF, KR, TT)

DS 10.10: Vortrag

Montag, 26. März 2012, 17:45–18:00, EB 301

The multiferroic, geometric frustrated CuCrO₂ compound: a case of the p−d hybridization spin-charge coupling? — •Matthias Frontzek, Georg Ehlers, and Andrey Podlesnyak — Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA

Multiferroic materials have become of interest for their unusual low-temperature properties in general, and in particular for the observation that one can affect their magnetic structure through an electric field and their electric polarization through a magnetic field. The delafossite CuCrO₂, which crystallizes in the rhombohedral R3m space group, is a multiferroic compound with an apparent strong coupling of spin and charge. In contrast to other multiferroic compounds CuCrO₂ shows a spontaneous electric polarization upon antiferromagnetic ordering without an accompanying structural phase transition, although a slight in-plane lattice distortion has been measured.

In our contribution, we present a detailed study on CuCrO₂ single crystals using neutron diffraction and spectroscopy as well as pulsed magnetic field measurements up to 60 T of the electric polarization. Based on our study we will show a revised magnetic structure model and present a model Hamiltonian including in-plane next-next nearest neighbor and inter-layer exchange interaction. We will stress the importance of the latter for the multiferroic properties and will show evidence based on the high field polarization measurements that the proposed p−d hybridization spin-charge coupling mechanism needs to be modified.