材料期刊网

The spin Hamiltonian parameters (zero-field splitting D, g factors and hyperfine structure constants) and local structure as well as their concentration dependences for Cd(1-x)Mn(x)S quantum dots are theoretically investigated from the perturbation formulae of these parameters for a 3d(5) ion under trigonally distorted tetrahedra. The impurity Mn(2+) is found not to occupy exactly the host Cd(2+) site in the CdS quantum dots but to experience an inward displacement 0.041 angstrom towards the ligand triangle along the C(3)-axis because of the size mismatching substitution and the internal stress. As compared with bulk CdS : Mn(2+), the larger impurity displacement and stronger Mn(2+) 3d-3s orbital admixture in the Cd(1-x)Mn(x)S quantum dots suitably account for the higher zero-field splitting and hyperfine structure constant, respectively. The impurity axial displacement and the Mn(2+) 3d-3s orbital admixture in the Cd(1-x)Mn(x)S quantum dots may exhibit an approximately cubic increase with increasing the Mn concentration x from 0.001 to 0.15.