Free spin-fluctuating lattice polarons as an alternative to small polarons

Abstract High-binding-energy small polarons contradict stability condition for the lattice. In magnetic semiconductors and manganites above the Curie point combined low-mobility magnetic-lattice polarons are possible. The free electron (hole) self-trapping occurs due to fluctuations of their spins following the fluctuations of the local magnetic moment, and to the lattice polarization.