Thesis presented July 02, 2007

Abstract:
The presence of a two-dimensional hole gas in a (Cd,Mn)Te quantum well induces a ferromagnetic interaction between the localized spins of the diluted magnetic semiconductor. We have developed a new method for the doping, which uses electron traps at the surface of the sample; this allows us to expand the range of experimentally accessible values of the density of carriers and of localized spins. The magnetic properties were measured through magneto-optical spectroscopy (photoluminescence). The critical temperature was measured to be higher than the Curie-Weiss temperature, which we tentatively ascribe to the presence of disorder. Local photoluminescence spectra allow us to draw maps of the spontaneous magnetization, of the carrier density and of the density of localized spins. The fluctuations of carrier density are larger in the surface-doped samples than in Nitrogen-doped samples, with a direct influence on the fluctuations of the spontaneous magnetization.

Keywords:
Spintronics, II-VI Semiconductors, Ferromagnetism, Doping, Disorder

On-line thesis.