Field pulse induced magnetic memory effect at room temperature in exchange coupled NiFe2O4/NiO nanocomposites
We report a room temperature (RT) magnetic memory effect induced by pulsed magnetic field in an assembly of Ferrimagnetic (FiM) and antiferromagnetic (AFM) exchange biased NiFe2O4/NiO nanocomposites. After cooling the system at low magnetic field (H = 200 Oe) combined with a series of field pulse treatment at several intermittent temperatures from 400 K to 100 K, the warming-up magnetization curve can exhibit a magnetization memory at the temperatures where field pulse was applied. Based on magnetic memory measured under different conditions, the magnitude of memory effect is revealed to be tunable by different pulsed-field strength and field pulse sequence, and it is insensitive to the low temperature time magnetization relaxation M(t) treatment. The origin of this field pulse driven memory effect can be understood in terms of the multiple distribution of magnetic state with different energy scales including the interfacial exchange interactions from the FiM and AFM phases.