石墨烯磁势垒量子点的能级结构

The energy-level structures of the graphene quantum dot induced by the magnetic barriers

研究了磁势垒量子点中有质量和无质量Dirac粒子的能级结构。通过求解Dirac方程,利用数值计算出圆内圆外磁矢势方向相同和相反以及有质量时量子点的能谱结构。研究表明,当圆内圆外的磁矢势方向相同时,随着量子点半径的增加,能级的变化体现出量子点内外磁场的竞争关系。与量子点内外的磁矢势方向相同显著不同,量子点内外的磁矢势方向相反时,量子点外的磁场占主导地位,其引起的朗道能级始终出现。质量的引进让系统转化为一个反量子点,且有质量Dirac粒子能级的平方获得一个跟质量相关的平移。

The energy-level structures of the graphene quantum dot influenced by magnetic barrier is investigated. Under the condition of the magnetic fields inside and outside the dot are parallel, as increase of the dot size, the energy-level structure are determined by the competition of two magnetic. The accompanying Landau levels from the field outside the dot always appear when the directions of the two vector potentials are mutually anti-parallel. The addition of the mass makes the dot to be an antidot, whereas the squared energy levels gain a constant associated with the mass.