Jahn-Teller vibrational anisotropy determines the magnetic structure in orthomanganites - art. no. 052403

It is demonstrated that a critical Mn-O-Mn angle determines a crossover bet ween Q(2) and Q(3) Jahn-Teller vibrational modes in O' orthomanganites, whi ch is coincident with a sudden variation of the ferromagnetic moment. The r ole played by the vibrational anisotropy Q(3)/Q(2) in charge/orbital orderi ng is discussed. Our results suggest that vibrational anisotropy can be at the origin of the phase separation mechanism that determines colossal magne toresistance in low-T-C manganites.