Acceleration of polaron induced by site effective mass increment in organic ferromagnets

Abstract

Abstract The polaron dynamics in organic ferromagnets (OFs) is investigated theoretically by considering the increment of site effective mass originating from the attachment of spin radicals. In spite of the increase of polaron effective mass, the results reveal two opposite effects on the polaron velocity caused by the increment of site effective mass. One is the normal decrease of the polaron velocity with the increment of site effective mass. The other is the abrupt acceleration of the polaron from below the sound velocity to the supersonic velocity upon a critical value of the site effective mass increment. Mechanism analysis shows that the acceleration of the polaron is attributed to the reduction of critical decoupling field for optical and acoustic deformations caused by the site effective mass increment. The second effect further depends on the polaron spin due to the existence of spin-dependent intrinsic dipole of the polarons. This work indicates the potential of high polaron mobility and efficient spin filtering effect under low electric fields in OFs.