Temperature dependent memory effects in the bilayer manganite (La0.4Pr0.6)(1.2)Sr1.8Mn2O7 - art. no. 092408

We report on the low-temperature resistance and magnetization of a single c rystal of the bilayer manganite (La0.4Pr0.6)(1.2)Sr1.8Mn2O7. In zero field the sample is an insulator at all temperatures while at fields larger than 3 T a transition to a ferromagnetic metallic state is observed. Below 50 K the sample shows a pronounced memory effect, in which both resistivity and magnetization become dependent on the magnetic history and clearly demonstr ate hysteretic behavior. At these low temperatures a difference in zero-fie ld resistivity before and after magnetization of six orders of magnitude ha s been measured. The relaxation of the memory effect follows a stretched ex ponential function with a characteristic decay time of 5 hours at 10 K. whi ch decreases to less than 1 ms above 40 K. These low-temperature properties can be related to magnetostriction data, indicating the presence of a fiel d-induced change in the orbital occupancy of the e(g) electrons of Mn3+.