Magneto-Elastic Phase Transitions In One-Dimensional Systems

The magneto-elastic phase diagram in one-dimensional systems relating to the interplay between magnetism and lattice distortion is studied in a double-exchange and super-exchange model considering classical localized spins and the limit of large Hund's coupling. At low super-exchange interaction energy, a phase transition occurs between electron-full ferromagnetic distorted and electron-empty antiferromagnetic undistorted phases via phase separation. In this case, all electrons and lattice distortions are found within the ferromagnetic domain. For higher super-exchange interaction energy, phase separations consisting of two-or three-site distorted independent magnetic polarons separated by electron-empty undistorted antiferromagnetic links are obtained. In this regime, each polaron contains an electron, leading to a Wigner crystallization. The lattice distortion and charge distribution inside the polarons are also calculated.