High magnetic-field study of the magnetization of layered manganite Nd2-2xSr1+2xMn2O7 single crystals

The magnetization of Nd2-2xSr1+2xMn2O7 layered manganite single crystals (with x = 0.5, 0.4, 0.25) has been studied using high magnetic fields up to 30T at 4.2 K. In these compounds, which are antiferromagnetic at low temperatures, induced metamagnetic transitions have been observed. These transitions become very sharp for doping level values in the range x = 0.25-0.4, reaching saturation-like behavior and displaying a large hysteresis. Maximum field magnetization is much lower than expected for the full ferromagnetic configuration of the Nd and Mn moments, and a large high field susceptibility is observed beyond the transition. The observed magnetization at maximum held within the ab-plane is lower (up to a 17%) than along the c direction. However, the value of the critical magnetic field of the transition is in all the cases larger for the magnetization within ab than along c. These transitions have been ascribed to spin-flipping within the Mn moment sublattice. (C) 2001 Elsevier Science B.V. All rights reserved.