Seminarium Fizyki Ciała Stałego

The ODMR technique allows us to study the local properties of magnetic ions incorporated in well-defined positions of the nanostructure. The basic information extracted from the ODMR spectra is the energy level structure of the Mn$^{2+}$ ion, which depends, e.g., on the local strain. Although the ODMR technique in diluted magnetic semiconductors is sensitive selectively to the magnetic ions, the detailed analysis of the measured signal reveals interactions within the magnetic ion system or between ions and charge carriers and the temperatures of the subsystems.The nominally undoped (Cd,Mn)Te/(Cd,Mg)Te quantum wells are typically p-type. The hole gas originates from the background doping of the (Cd,Mg)Te barrier material or the surface states. Depending on the conditions, the ODMR signal is affected by the carriers present in the sample in two ways. The first effect is the shift between the ODMR signals obtained on neutral and charged exciton (Knight shift). The second one is a change in the spin-lattice relaxation (SLR) rate in the presence of the carriers. The shape of the ODMR signal keeps the information about the temperature of the magnetic ions involved in the absorption of the MW. Studying it in detail can provide even more information about interactions with charge carriers.