Discontinuous transition effects in manganites: magnetization study in the paramagnetic phase

Abstract The magnetization M ( H , T ) of La-based manganites in the paramagnetic phase is studied. La 0.67 Ca 0.33 MnO 3 , La 0.8 MnO 3 and La 0.60 Y 0.07 Ca 0.33 MnO 3 ferromagnetic metals show first-order phase transition features near T C with maxima in d M /d H and kinks in H / M vs. T . Such effects are absent in ferromagnetic insulator La 0.67 Cd 0.25 MnO 3 . Results are analyzed with a Landau energy expansion up to sixth power in M and the anomalies related with the electronic condensation and magneto-elastic energies coupling to the magnetic degree of freedom.