Institute for Microstructural Sciences, National Research Council of Canada, Ottawa, Canada.
Phys Rev Lett. 2009 Dec 11;103(24):246805. doi: 10.1103/PhysRevLett.103.246805. Epub 2009 Dec 10.
We show that the ground state and magnetization of the macroscopically degenerate shell of electronic states in triangular gated graphene quantum dots depends on the filling fraction of the shell. The effect of degeneracy, finite size, and electron-electron interactions are treated nonperturbatively using a combination of density functional theory, tight-binding, Hartree-Fock and configuration interaction methods. We show that electronic correlations play a crucial role in determining the nature of the ground state as a function of filling fraction of the degenerate shell at the Fermi level. We find that the half-filled charge neutral shell leads to full spin polarization but this magnetic moment can be completely destroyed by adding a single electron.
我们表明，在三角栅控石墨烯量子点中，电子态宏观简并壳层的基态和磁化强度取决于壳层的填充分数。使用密度泛函理论、紧束缚、哈特ree-Fock 和组态相互作用方法的组合，我们非微扰地处理了简并、有限大小和电子-电子相互作用的影响。我们表明，电子相关在确定基态的性质方面起着至关重要的作用，这是作为费米能级处简并壳层填充分数的函数。我们发现，半满的中性电荷壳层导致完全的自旋极化，但通过添加单个电子可以完全破坏这个磁矩。
