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

DOI: 10.1103/PhysRevB.93.180403 DOI Help

Authors: R. D. Johnson (University of Oxford; ISIS facility, Rutherford Appleton Laboratory-STFC) , D. D. Khalyavin (ISIS facility, Rutherford Appleton Laboratory-STFC) , Pascal Manuel (ISIS facility, Rutherford Appleton Laboratory-STFC) , A. Bombardi (Diamond Light Source) , C. Martin (Laboratoire CRISMAT) , L. C. Chapon (Institut Laue-Langevin) , P. G. Radaelli (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 93

State: Published (Approved)
Published: May 2016
Diamond Proposal Number(s): 5693

Abstract: Through a combination of neutron diffraction and Landau theory we describe the spin ordering in the ground state of the quadruple perovskite manganite CaMn 7 O 12 —a magnetic multiferroic supporting an incommensurate orbital density wave that onsets above the magnetic ordering temperature, T N1 =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 Mn 3+ sites via trilinear magneto-orbital coupling. Our phenomenological model also shows that, above T N2 =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 T N1 and the unusual temperature dependence of the electrical polarization.

Subject Areas: Materials, Physics

Instruments: I16-Materials and Magnetism