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 (w ith x = 0.5, 0.4, 0.25) has been studied using high magnetic fields up to 3 0T at 4.2 K. In these compounds, which are antiferromagnetic at low tempera tures, induced metamagnetic transitions have been observed. These transitio ns become very sharp for doping level values in the range x = 0.25-0.4, rea ching saturation-like behavior and displaying a large hysteresis. Maximum f ield magnetization is much lower than expected for the full ferromagnetic c onfiguration of the Nd and Mn moments, and a large high field susceptibilit y 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 tr ansitions have been ascribed to spin-flipping within the Mn moment sublatti ce. (C) 2001 Elsevier Science B.V. All rights reserved.