Temperature dependence of 55Mn NMR spectrum in La0.5Ba0.5MnO3

Abstract 55 Mn NMR spectra have been measured from 4.2 up to 225 K in the A-site disordered La 0.5 Ba 0.5 MnO 3 . The internal magnetic field estimated from their peak frequencies decreases more slowly comparing with that observed in the A-site ordered LaBaMn 2 O 6 . While the phase transition from paramagnetic state to ferromagnetic state at 330 K in LaBaMn 2 O 6 is considered to be the second order transition, the ferromagnetic phase transition at 280 K in La 0.5 Ba 0.5 MnO 3 seems to be the first order transition as observed in various disordered manganites.