Sun Wei, Wang Wenxuan, Chen Dong, Cheng Zhenxiang, Wang Yuanxu
Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004, People's Republic of China.
Nanoscale. 2019 May 28;11(20):9931-9936. doi: 10.1039/c9nr01510h. Epub 2019 May 9.
Exploring two-dimensional (2D) materials with both ferromagnetic and ferroelectric properties is scientifically interesting and of great technical importance to numerous functionalities in nanoscale devices. In this work, we have demonstrated a strong magnetoelectric coupling that appeared in the 2D FeI/InSe van der Waals heterostructure. FeI layers undergo a transition from ferromagnetic to antiferromagnetic by reversing the direction of ferroelectric polarization. First-principles calculation predicts a new magnetoelectronic coupling mechanism which is completely different from the Dzyaloshinskii-Moriya (DM) effect in multiferroic materials. Because of the polarization discontinuity at the interface, the valence states of Fe ions change between +2 and +3 for two different polarization directions, leading to the magnetic interaction variation between the direct exchange and I ion mediated superexchange. Moreover, metallic 2D electron gas (2DEG) transfers from the surface of FeI to InSe when the polarization reverses, which induces the spin polarization of the heterostructure varying from 93% to 0%. Our work is the first realization of manipulation magnetism by an electric field in full 2D van der Waals heterostructures.
探索具有铁磁和铁电特性的二维（2D）材料在科学上具有重要意义，并且对于纳米级器件中的众多功能具有重大技术价值。在这项工作中，我们展示了二维FeI/InSe范德华异质结构中出现的强磁电耦合。通过反转铁电极化方向，FeI层经历从铁磁到反铁磁的转变。第一性原理计算预测了一种全新的磁电耦合机制，这与多铁性材料中的Dzyaloshinskii-Moriya（DM）效应完全不同。由于界面处的极化不连续性，对于两个不同的极化方向，Fe离子的价态在+2和+3之间变化，导致直接交换和I离子介导的超交换之间的磁相互作用发生变化。此外，当极化反转时，金属二维电子气（2DEG）从FeI表面转移到InSe，这使得异质结构的自旋极化率从93%变为0%。我们的工作首次在全二维范德华异质结构中实现了通过电场操纵磁性。
