Ren Wen-Ning, Jin Kui-Juan, Wang Jie-Su, Ge Chen, Guo Er-Jia, Ma Cheng, Wang Can, Xu Xiulai
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
Sci Rep. 2021 Feb 2;11(1):2744. doi: 10.1038/s41598-021-82394-y.
The emergence of ferromagnetism in two-dimensional van der Waals materials has aroused broad interest. However, the ferromagnetic instability has been a problem remained. In this work, by using the first-principles calculations, we identified the critical ranges of strain and doping for the bilayer CrGeTe within which the ferromagnetic stability can be enhanced. Beyond the critical range, the tensile strain can induce the phase transition from the ferromagnetic to the antiferromagnetic, and the direction of magnetic easy axis can be converted from out-of-plane to in-plane due to the increase of compressive strain, or electrostatic doping. We also predicted an electron doping range, within which the ferromagnetism can be enhanced, while the ferromagnetic stability was maintained. Moreover, we found that the compressive strain can reverse the spin polarization of electrons at the conduction band minimum, so that two categories of half-metal can be induced by controlling electrostatic doping in the bilayer CrGeTe. These results should shed a light on achieving ferromagnetic stability for low-dimensional materials.
二维范德华材料中铁磁性的出现引起了广泛关注。然而，铁磁不稳定性一直是个问题。在这项工作中，通过第一性原理计算，我们确定了双层CrGeTe中应变和掺杂的临界范围，在该范围内铁磁稳定性可以增强。超出临界范围，拉伸应变会诱导从铁磁到反铁磁的相变，并且由于压缩应变或静电掺杂的增加，易磁化轴方向可以从面外转换为面内。我们还预测了一个电子掺杂范围，在该范围内铁磁性可以增强，同时保持铁磁稳定性。此外，我们发现压缩应变可以反转导带最小值处电子的自旋极化，从而通过控制双层CrGeTe中的静电掺杂可以诱导出两类半金属。这些结果应该为实现低维材料的铁磁稳定性提供启示。
