An unconventional magnetoresistance in CoFe2O4 core-BiFeO3 shell composite.

Magnetodielectric and magnetoresistance measurements are performed on the 40%CoFe2O4−60%BiFeO3 core-shell composite above room temperature. The high value of positive magnetodielectric behavior originates due to Maxwell-Wagner effect which is very much supportive with negative MR behavior. The room temperature magnetic field dependent MR indicates the conventional spin polarized tunneling mechanism through interface. A spin-valve action is spotted in MR at 350K with an irreversibility. The most interesting is the MR behavior at 400K. A number of peculiar behavior has been observed which is very unusual at high temperature. [ABSTRACT FROM AUTHOR]