Structure and Spin-Glass Properties of Cd,,Mn,,S Diluted Magnetic Semiconductor Quantum Dots

Abstract- Cdo.5Mno.5S diluted magnetic semiconductor (DMS) quantum dots (QDs) of crystallite size ranging from 24 A to the bulk have been chemically synthesized using an aqueous solution precipitation method and thermal annealing. Subsequent characterization indicates that the "as prepared " material is of the cubic zinc blende structure which evolves with increasing size to the bulk hexagonal wurtzite structure. Magnetic properties of the DMS QDs have been measured with a SQUID magnetometer. A transition from a paramagnetic to a spin-glass (SG) state at a critical temperature T, has been observed. Size dependence measurements on Tf indicate a minimum size for SG formation. Relaxation in isothermal remanent magnetization has also been measured and shows a power law decay. I