Spin polarons and variable range hopping in magnetically disordered systems

Magnetic polarons in magnetically disordered systems (for brevity, spin-glass polarons) are in one respect very unlike other polarons: Usual polaron hopping at low T proceeds via tunneling, and these polarons do not affect the T dependence of the hopping rate, while the spin-glass polaron tunneling is suppressed by the disorder, and their hopping proceeds via activation for all T. It gives rise to the reentrance of the simple activated T dependence of variable range hopping conductivity at very low T. Recent experiments in CdMnTe are discussed.