Ferromagnetism in quantum dots*

We consider d⁰ ferromagnetism where Zn vacancies in ZnS semiconductor nanocrystals (NC) (quantum dots and nanowires). The absence of Zn atoms exhibits the ferromagnetic order at room temperatures. We find a magnetic moment in large quantum dots and nanowires by introducing a new model, the surface-bulk model, where a NC magnetic moment is presented as a sum of the surface and bulk contributions. We find how the magnetic moment depends on the concentration and size of a nanocrystal. In addition we discovered the large, three orders of magnitude discrepancy between the experimental and calculated magnetic moments. Such a large disagreement between the experiment and theory is explained due to the condensation of impurities inside a nanocrystal.