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Nature of spin-lattice coupling in two-dimensional CrI3 and CrGeTe3
Science China Physics, Mechanics & Astronomy ( IF 6.4 ) Pub Date : 2021-06-30 , DOI: 10.1007/s11433-021-1717-9
Jing Li , JunSheng Feng , PanShuo Wang , ErJun Kan , HongJun Xiang

Spin-lattice (SL) coupling plays an important role in spintronic applications given its effects on magnetic, ferroelectric, optical, and thermodynamic properties. Experiments and theoretical calculations have revealed a large SL coupling effect in CrGeTe3 and CrI3 monolayers. However, the microscopic origin of SL coupling in these systems is still unclear. In this work, we develop a systematic method to explore the atomistic mechanism of SL coupling based on the density functional theory. We find that the first- and second-order SL couplings in ternary system CrGeTe3 are considerably stronger than those in binary system CrI3. For the first-order SL coupling, the Cr ions of the magnetic pair and Ge ions positively contribute to the strain enhancement of ferromagnetism in CrGeTe3. However, the Cr ions provide a negative contribution in CrI3. Furthermore, our tight-binding analysis suggests that the p-d hopping in CrGeTe3 gradually decreases with the tensile strain, rapidly enhancing the ferromagnetism under the tensile strain. The large frequency shifts in CrGeTe3 are caused by the large second-order exchange derivatives (one type of second-order SL coupling) of the Cr ions of the magnetic pair.



中文翻译:

二维 CrI3 和 CrGeTe3 中自旋晶格耦合的性质

鉴于自旋晶格 (SL) 耦合对磁、铁电、光学和热力学性质的影响,自旋电子学应用中起着重要作用。实验和理论计算揭示了 CrGeTe 3和CrI 3单层中的大 SL 耦合效应。然而,这些系统中 SL 耦合的微观起源仍不清楚。在这项工作中,我们开发了一种基于密度泛函理论的系统方法来探索 SL 耦合的原子机制。我们发现,在三元系统的第一级和第二级SL联轴器CrGeTe 3比在二进制值CrI要强大得多3. 对于一阶 SL 耦合,磁性对的 Cr 离子和 Ge 离子对 CrGeTe 3中铁磁性的应变增强有积极贡献。然而,Cr离子在CrI 3 中提供负贡献。此外,我们的紧束缚分析表明,CrGeTe 3中的pd跳跃随着拉伸应变逐渐降低,在拉伸应变下迅速增强铁磁性。CrGeTe 3中的大频率偏移是由磁对的 Cr 离子的大二阶交换导数(一种二阶 SL 耦合)引起的。

更新日期:2021-07-06
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