The spin polarized states in pristine silicon thin films

• 作 者: 孙家涛
• 机 构: 中国科学院物理研究所
• 出 处: 中国真空学会2016学术年会
• 发表日期: 2016年5期
• 关键词: 密度泛函理论计算 硅薄膜 量子谷霍尔效应 量子反常霍尔效应

　　The introduction of spin polarization of electrons in materials consisting of d0 lightelements like carbon and silicon is strongly desirable for spintronics applications.It have beenwidely accepted that both elements in single component are not taken as ferromagnetic candidatesbecause of the negligible magnetic exchange interaction and the absence of odd paired electrons.The ferromagnetism within them has to be made by introducing ferromagnetic impurity,atomicvacancy,edge functionalization,atomic chain along the edges,grain boundary,and proximity withferromagnetic neighbors etc.These special surface or interface structures require atomicallyprecise control which significantly increases experimental uncertainty and theoreticalunderstanding.By means of density functional theory(DFT)computations,we found that the spinpolarized state like ferromagnetism and antiferromagnetism can be introduced in a series of pristine silicon thin films without any alien components.The key point to this aim is the formationof graphene-like hexagonal structures making a spin-polarized Dirac fermion with half-filling.Thenegligible ratio of the nearest-neighbor electronic hopping parameter t over the on-site Hubbardrepulsion might push the ground state of silicon thin film to a strongly correlated systemrendering the previous view of negligible correlation in light elements not solid.The resultingfundamental physics such as quantum valley Hall effect(QVHE),quantum anomalous Hall effect(QAHE)and magnetoelectric effect will be discussed.These studies indicate that the conventionalsemiconducting materials consisting of light nonmagnetic elements show promise toward thespintronic and optoelectronic devices.