Modulated spin helicity stabilized by incommensurate orbital density waves in a quadruple perovskite manganite

Abstract : Through a combination of neutron diffraction and Landau theory we describe the spin ordering in the ground state of the quadruple perovskite manganite CaMn7O12 - a magnetic multiferroic supporting an incommensurate orbital density wave that onsets above the magnetic ordering temperature, TN1=90 K. The multi-k magnetic structure in the ground state was found to be a nearly-constant-moment helix with modulated spin helicity, which oscillates in phase with the orbital occupancies on the Mn3+ sites via trilinear magneto-orbital coupling. Our phenomenological model also shows that, above TN2=48 K, the primary magnetic order parameter is locked into the orbital wave by an admixture of helical and collinear spin density wave structures. Furthermore, our model naturally explains the lack of a sharp dielectric anomaly at TN1 and the unusual temperature dependence of the electrical polarization. © 2016 American Physical Society.
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Soumis le : mardi 16 juillet 2019 - 11:33:22
Dernière modification le : jeudi 31 octobre 2019 - 16:48:02

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R.D. Johnson, D.D. Khalyavin, P. Manuel, A. Bombardi, C. Martin, et al.. Modulated spin helicity stabilized by incommensurate orbital density waves in a quadruple perovskite manganite. Physical Review B : Condensed matter and materials physics, American Physical Society, 2016, 93 (18), pp.180403. ⟨10.1103/PhysRevB.93.180403⟩. ⟨hal-02184774⟩

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