Colossal magnetoresistance and re-entrant charge ordering in single crystalline two layer Mn perovskite LaSr2Mn2O7

We report on the resistivity (ρab), magnetisation (M), and X-ray synchrotron measurements on a single crystal of the two-layer manganite LaSr2Mn2O7. ρab showed a maximum at 180 K and increased rapidly for T<80 K. In a field of 8 T, colossal magnetoresistance (CMR) data showed two maxima at 150 and 40 K. In low fields, M (H∥ab) showed also two maxima at these temperatures. X-ray investigations revealed satellite reflections whose intensity showed a strong maximum at 170 K followed by a re-entrant behaviour below about 40 K. The data seem to reflect the structural, charge and orbital degrees of freedom present in this compound.