Real-space magnetic imaging of the multiferroic spinels MnV2O4 and Mn3O4
Real-space magnetic imaging of the multiferroic spinels MnV2O4 and Mn3O4
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DOI：
10.1103/physrevmaterials.2.064407
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发表时间：
2018-06
影响因子：
3.4
通讯作者：
B. Wolin;Xiaofei Wang;T. Naibert;S. Gleason;G. MacDougall;H. Zhou;H. Zhou;S. Cooper;R. Budakian
中科院分区：
文献类型：
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作者：
B. Wolin;Xiaofei Wang;T. Naibert;S. Gleason;G. MacDougall;H. Zhou;H. Zhou;S. Cooper;R. Budakian
控制材料中的多铁性行为将使各种技术应用的发展成为可能。然而，在大多数材料中，驱动多铁性行为的确切机制尚不清楚。两种这样的材料是尖晶石MnV2O4和Mn3O4，其中的机械应变被认为在决定磁性行为中起作用。MnV2O4的体积研究产生了相互矛盾和不确定的结果，部分原因是中尺度磁性不均匀性的存在，使体积测量的解释复杂化。为了研究锰基尖晶石材料的亚微米尺度磁性能，我们对不同机械应变水平下的MnV2O4样品进行了磁力显微镜（MFM）观察。我们还使用晶粒映射技术对Mn3O4进行了空间注册MFM。这些局部研究揭示了两种材料的磁性结构中100纳米尺度的“条纹”调制。在MnV2O4中，这些条纹的磁化强度估计为Mz $ $\约$ 105 A/m，与之前报道的饱和磁化强度相同。在强磁场中冷却只在低应变的MnV2O4样品中消除了条纹图案。这些材料的纳米级磁结构不均匀性对磁场控制非常敏感，这一发现需要对理论建议进行修订，并重新解释有关这些mn基尖晶石的低温相和磁场可调特性的实验数据。
Controlling multiferroic behavior in materials will enable the development of a wide variety of technological applications. However, the exact mechanisms driving multiferroic behavior are not well understood in most materials. Two such materials are the spinels MnV2O4 and Mn3O4, where mechanical strain is thought to play a role in determining magnetic behavior. Bulk studies of MnV2O4 have yielded conflicting and inconclusive results, due in part to the presence of mesoscale magnetic inhomogeneity, which complicates the interpretation of bulk measurements. To study the sub-micron-scale magnetic properties of Mn-based spinel materials, we performed magnetic force microscopy (MFM) on MnV2O4 samples subject to different levels of mechanical strain. We also used a crystal grain mapping technique to perform spatially registered MFM on Mn3O4. These local investigations revealed 100-nm-scale "stripe" modulations in the magnetic structure of both materials. In MnV2O4, the magnetization of these stripes is estimated to be Mz $\approx$ 105 A/m, which is on the order of the saturation magnetization reported previously. Cooling in a strong magnetic field eliminated the stripe patterning only in the low-strain sample of MnV2O4. The discovery of nanoscale magnetostructural inhomogeneity that is highly susceptible to magnetic field control in these materials necessitates both a revision of theoretical proposals and a reinterpretation of experimental data regarding the low-temperature phases and magnetic-field-tunable properties of these Mn-based spinels.