Linear and nonlinear critical magnetic properties and transport in Nd0.75Ba0.25MnO3 single crystal: evidence for its anomalous critical behavior near TC

Abstract The data on the resistance and magnetoresistance (MR) as well as measurements of the linear and nonlinear susceptibilities are presented for a Nd 0.75 Ba 0.25 MnO 3 single crystal with the Curie temperature T C ≈129 K . Although this compound remains insulating in the ferromagnetic state, its resistance has an anomaly near T C and it reveals the colossal magnetoresistance. The data on the magnetic response are well described by the dynamic scaling theory for 3D isotropic ferromagnets in the paramagnetic critical region at τ>τ ∗ ≈0.11, τ =( T − T C )/ T C . Below τ ∗ an anomalous critical behavior is found that suggests the coexistence of two magnetic phases. This behavior is discussed in terms of a phase separation which can occur in the moderately doped manganites exhibiting an orbital ordering.