Phase diagram of multiferroic KCu3As2O7(OD)(3)

Article

关键词: KAGOME ANTIFERROMAGNET;    POLARIZATION;    DIFFRACTION;    SYMMETRY;   

DOI  :  10.1103/PhysRevB.95.214415

来源: SCIE

【 摘 要 】

The layered compound KCu3As2O7(OD)(3), comprising distorted kagome planes of S = 1/2 Cu2+ ions, is a recent addition to the family of type-II multiferroics. Previous zero-field neutron diffraction work has found two helically ordered regimes in KCu3As2O7(OD)(3), each showing a distinct coupling between the magnetic and ferroelectric order parameters. Here, we extend this work to magnetic fields up to 20 T using neutron powder diffraction, capacitance, polarization, and high-field magnetization measurements, hence determining the H-T phase diagram. We find metamagnetic transitions in both low-temperature phases around mu H-0(c) similar to 3.7 T, which neutron powder diffraction reveals to correspond to rotations of the helix plane away from the easy plane, as well as a small change in the propagation vector. Furthermore, we show that the sign of the ferroelectric polarization is reversible in a magnetic field, although no change is observed (or expected on the basis of the magnetic structure) due to the transition at 3.7 T. We finally justify the temperature dependence of the polarization in both zero-field ordered phases by a symmetry analysis of the free energy expansion, and attempt to account for the metamagnetic transition by adding anisotropic exchange interactions to our existing model for KCu3As2O7(OD)(3).

【 授权许可】

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