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arXiv · 1608.00823

Stress-induced magnetic domain selection reveals a conical ground state for the multiferroic phase of Mn2GeO4

J. S. White·T. Honda·R. Sibille·N. Gauthier·V. Dmitriev·Th. Strässle·Ch. Niedermayer·T. Kimura·M. Kenzelmann
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Abstract

At ambient pressure (P) and below 5.5 K, olivine-type Mn2GeO4 hosts a multiferroic (MF) phase where a multicomponent, i.e., multi-k magnetic order generates spontaneous ferromagnetism and ferroelectricity (FE) along the c axis. Under high P the FE disappears above 6 GPa, yet the P evolution of the magnetic structure remained unclear based on available data. Here we report high P single crystal neutron diffraction experiments in theMF phase at T = 4.5 K.We observe clearly that the incommensurate spiral component of the magnetic order responsible for FE varies little with P up to 5.1 GPa. With support from high P synchrotron x-ray diffraction measurements at room temperature (T), the P driven suppression of FE is proposed to occur as a consequence of a crystal structure transition away from the olivine structure. In addition, in the low T neutron scattering experiments an emergent nonhydrostatic P component, i.e., a uniaxial stress, leads to the selection of certain multi-k domains. We use this observation to deduce a double-k conical magnetic structure for the ambient P ground state, this being a key ingredient for a model description of the MF phase.

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J. S. White, T. Honda, R. Sibille, N. Gauthier, V. Dmitriev, Th. Strässle, Ch. Niedermayer, T. Kimura, M. Kenzelmann. 2016-08-02. Stress-induced magnetic domain selection reveals a conical ground state for the multiferroic phase of Mn2GeO4. https://doi.org/10.1103/physrevb.94.024439

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