报告题目：2D magnetism by first-principles calculations

报告人：Jiatao Sun（孙家涛）

报告时间： 2017年3月31日 上午10：00-11：00

报告地点：物理科学与技术学院，新楼5楼多功能报告厅

Abstract: 2D materials beyond graphene have received great interest because of their novel physical properties like magnetism, superconductivity, optics etc. The introduction of spin polarization in 2D materials consisting of d0 light elements like carbon and silicon is strongly desirable promising for potential applications in spintronics. It have been widely accepted that both elements in single component are not taken as ferromagnetic candidates because of the negligible magnetic exchange interaction and the absence of odd paired electrons. The ferromagnetism has to be made by introducing ferromagnetic impurity, atomic vacancy, edge functionalization, atomic chain along the edges, grain boundary, and proximity with ferromagnetic neighbors etc. These specially designed surface or interface structures require atomically precise control which significantly increases experimental uncertainty and burden of theoretical understanding. By means of first-principles calculations, we found that the spin polarized states like ferromagnetism and antiferromagnetism can be introduced on pristine silicon surfaces without any alien components. The key point to this aim is the formation of graphene-like hexagonal structures making a spin-polarized Dirac fermion with half-filling. The negligible ratio of the nearest-neighbor electronic hopping parameter t over the on-site Hubbard repulsion Ũ0 might push the ground state of silicon thin film to a strongly correlated system rendering the previous view of negligible correlation in light elements not solid. The implication of our results for surface spin transport such as quantum valley Hall effect, quantum anomalous Hall effect and magnetoelectric effect will be discussed.

个人简介：孙家涛博士自1998年至2005年在山东大学材料科学与工程系学习并获得学士学位和硕士学位；2008年底毕业于中国科学院物理研究所，并获得博士学位；随后至新加坡国立大学和美国犹他大学从事博士后研究。2013年底加入中国科学院物理研究所，现为副研究员、博士生导师。申请人长期致力于利用第一性原理计算方法，研究低维量子体系以及新型二维原子晶体材料中的新奇物性及其调控；配合先进的实验手段，揭示实验现象的物理本质。

References

[1] Phys. Rev. B 83, 115419 (2011).

[2] Nanoscale, 8, 17854 (2016).

[3] Phys. Rev. B 94, 035427 (2016).

[4] 2D Materials 3, 035026 (2016).

邀请人：邱春印副教授