Experimental aspects of spin carrier interaction in II-VI DMSs: From carrier induced ferromagnetism to single spin quantum dots

Joël Cibert

Laboratoire Louis Néel, CNRS, BP166, 38042 Grenoble cedex 9, France

In spite of a surprising success of the mean field model of carrier induced ferromagnetism, it has been early recognized that localization and disorder may play an important role. II-VI semiconductors with Mn impurities constitute a model system, since the introduction of the localized spins and the electrical doping are independent. We will describe experimental features related to disorder in (Cd,Mn)Te quantum wells and to localization in CdTe quantum dots. In p-doped (Cd,Mn)Te quantum wells, effects of disorder were looked for (i) in the carrier dependence of the critical temperature (compared to the dependence of the spin susceptibility of the hole gas), (ii) in a comparison of the critical temperature to the Curie-Weiss temperature, and (iii) in the carrier dependence of the spontaneous magnetization including a study at sub-micrometer scale. Finally, the elaboration of CdTe quantum dots on ZnTe with a very low amount of Mn results in the spectroscopic observation of a single dot containing a single magnetic impurity.