Griffiths phase in diluted magnetic semiconductors.
We study the effects of disorder in the vicinity of the ferromagnetic transition in a diluted magnetic semiconductor in the strongly localized regime. We derive an effective polaron Hamiltonian, which leads to the Griffiths phase above the ferromagnetic transition point. The Griffiths-McCoy effects yield nonperturbative contributions to the dynamic susceptibility. We explicitly derive the long-time susceptibility, which has a pseudoscaling form, with the dynamic critical exponent being expressed through the percolation indices.
Galitski
V M
VM
Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, MD 20742-4111, USA.
Kaminski
A
A
Das Sarma
S
S