Abstract
Magnetic-field effects on the energy spectrum (Hofstadter butterfly) and the flat-band ferromagnetism are studied on a two-dimensional Kagomé lattice of quantum dots. Application of a perpendicular magnetic field destroys the flat-band ferromagnetism and induces a metal-insulator transition because the flat band has a finite dispersion. In the half-filled flat band, the ferromagnetic-paramagnetic transition and the metal-insulator one occur simultaneously at a magnetic field when the Coulomb interaction is strong. These phenomena can be observed in experiment under reasonable magnetic fields in artificial quantum dot superlattices.
- Received 14 November 2001
DOI:https://doi.org/10.1103/PhysRevB.65.081307
©2002 American Physical Society