K. Hirose — Page 2 | Searcharxiv

arXiv2000

Detailed analysis of scanning tunneling microscopy images of the Si(001) reconstructed surface with buckled dimers

The adequate interpretation of scanning tunneling microscopy (STM) images of the clean Si(001) surface is presented. We have performed both STM observations and {\it ab initio} simulations of STM images for buckled dimers on the clean Si(001) surface. By comparing experimental results with theoretical ones, it is revealed that STM images depend on the sample bias and the tip-sample separation. This enables us to elucidate the relationship between the corrugation in STM images and the atomic structure of buckled dimers. Moreover, to elucidate these changes, we analyze details of the spatial distributions of the $π$, $π^{\ast}$ surface states and $σ$, $σ^{\ast}$ Si-Si bond states in the local density of states which contribute to STM images.

cond-mat.mtrl-sci↗

arXiv2000

Density functional theory of spin-polarized disordered quantum dots

Using density functional theory, we investigate fluctuations of the ground state energy of spin-polarized, disordered quantum dots in the metallic regime. To compare to experiment, we evaluate the distribution of addition energies and find a convolution of the Wigner-Dyson distribution, expected for noniteracting electrons, with a narrower Gaussian distribution due to interactions. The tird moment of the total distribution is independent of interactions, and so is predicted to decrease by a factor of 0.405 upon application of a magnetic field which transforms from the Gaussian orthogonal to the Gaussian unitary ensemble.

cond-mat.mes-hall↗