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Fig. 1 | Crystal and band structures of MnI3 and In2Se3 monolayers, and their stacking configurations.
来自四川大学力学系的田晓宝、梁英团队通过组合二维铁电In2Se3和铁磁MnI₃材料构建In₂Se₃/MnI₃异质结，并预测了异质界面的磁电耦合特征。他们运用第一性原理计算方法，分析了其结构稳定性，揭示了界面接触特性与磁电耦合效应，探讨了层间距离的影响规律。他们研究发现，In₂Se₃/MnI₃异质结界面失配率约为0.56%，其形成能约为–31.40~–37.42 meV/Å2，表明其具有很好的稳定性和可行性。MnI₃在异质结中呈现稳定的4μB强面内铁磁性，表现出磁场强度可读能力。同时，通过调控异质结铁电层In2Se3的极化方向，可以实现界面的
Fig. 2 | Charge transfer.
In₂Se₃/MnI₃异质结之所以能够实现“电写磁读”，其磁电耦合机理主要是：1）铁电极化调控接触类型的变换主要源于极化翻转对功函数的巨大影响，极化方向的切换改变了两层材料的功函数差的正负属性，进而导致对齐费米能级时出现不同的接触类型。2）极化调控磁性性质，源于铁电极化通过改变了磁晶各项异性强度和磁易轴方向，实现调控MnI₃的磁矩方向和稳定性，其核心在于铁电极化能够对Mn-I的自旋轨道耦合（SOC）强度进行调控。3）通过对异质结结构的层间间距的研究发现，In₂Se₃/MnI₃异质结结构的具有稳定可调接触性和可调磁矩方向。
Fig. 3 | The effect of interlayer distance
作者对这一机理的呈现，为进一步设计多铁异质结界面的“电写磁读”能力提供思路。该文近期发表于npj Computational Materials 10: 238 (2024)，英文标题与摘要如下，点击左下角“阅读原文”可以自由获取论文PDF。
Tunable Schottky barriers and magnetoelectric coupling driven by ferroelectric polarization reversal of MnI3/In2Se3 multiferroic heterostructures
Tao Zhang, Hao Guo, Jiao Shen, Ying Liang, Haidong Fan, Wentao Jiang, Qingyuan Wang & Xiaobao Tian
Two-dimensional (2D) multiferroic materials are recognized as promising candidates for next-generation nanodevices due to their tunable magnetoelectric coupling and distinctive physical phenomena. In this study, we proposed a novel 2D multiferroic van der Waals heterostructure (vdWH) by stacking atomic layers of ferroelectric In2Se3 and ferromagnetic MnI3. Using first-principles calculations, we found that the MnI3/In2Se3 vdWH exhibit robust metallic conductivity across various spin and polarization states, preserving the distinctive band characteristics of isolated In2Se3 and MnI3. However, the alignment of Fermi levels causes the conduction band minimum (CBM) and valence band maximum (VBM) of In2Se3 and MnI3 to shift relative to their original band structures. Remarkably, the MnI3/In2Se3 with the upward polarization state of In2Se3 exhibits an Ohmic contact. Switching the polarization direction of In2Se3 from upward to downward can transform the MnI3/In2Se3 vdWH from an Ohmic contact to a p-type Schottky contact, while also modifying its dipole moment, magnetic strength and direction. Based on these properties of MnI3/In2Se3 vdWH, we designed the field-effect transistors (FETs) with high on/off rates and nonvolatile data storage device. Furthermore, the Schottky barrier heights (SBHs), magnetic moment, and dipole moment of MnI3/In2Se3 vdWH can also be effectively regulated by reducing the interlayer distance. With the continuous reduction of the interlayer distance of MnI3/In2Se3 vdWH, its easy magnetization axis is expected to shift from in-plane to out-of-plane. These findings offer new insights for the design and development of the next-generation spintronic and nonvolatile memory nanodevices.
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