Doping-controlled quantum magnetization plateau and high-field ferroelectricity in multiferroic Ni2-xTxV2O7 (T = Zn or Mn)

摘要

The synchronized observation of a quantum magnetization plateau and multiferroicity is of particular interest in frustrated antiferromagnets, but the modulation of two different fascinating phenomena is greatly challenging and urgently desired. Here, we report an efficient approach with chemical substitutions to achieve flexible control of a half quantum magnetization plateau and high-field ferroelectricity in the S = 1 skew-chain antiferromagnet Ni2V2O7. In Zn-doped cases, the half quantum magnetization plateau is remarkably broadened with an increasing concentration on dopants, such as a giant variation reaching 69.3% at x = 0.7, suggesting the existence of a larger spin gap than before. In contrast, the width of magnetization plateaus for Mn-doped samples pronouncedly shrinks about -37.4% at x = 0.2, and then tends to stabilization upon further increasing x. Intriguingly, we find that the end of half magnetization plateaus locates in the same position between two groups of samples. In particular, the nontrivial magnetoelectric coupling related with the high-field ferroelectricity performs an identical evolution for Ni2-xTxV2O7 (T = Zn or Mn) by sweeping magnetic fields. As a consequence, a close correlation between the half magnetization plateau and ferroelectricity is confirmed, indicating that the high-field polarization is derived from peculiar magnetic moments in Ni2V2O7. Possible origins for the Zn- and Mn-doping effects on the quantum magnetization plateau and multiferroicity are discussed. In addition, high-field phase diagrams with the plateau and ferroelectricity are constructed for these doped compounds. Therefore, these experimental findings open an additional avenue to tune the quantum magnetization plateau and magnetically induced ferroelectricity, simultaneously.

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