Exchange bias and vertical shift of the magnetic hysteresis loop in Co/BiFeO₃ bilayers

Abstract

To reveal the mechanism of interfacial exchange coupling, the magnetic hysteresis (M-H) loop of Co/BiFeO₃ bilayers deposited on (001) LaAlO₃ (LAO) substrates by magnetron sputtering was measured. The M-H loop displays a horizontal shift along the field axis coexisting with a vertical shift along the magnetization axis. The frozen uncompensated interfacial spins result in the EB effect, as demonstrated by the similar dependencies between EB and the vertical shift in temperature and BFO thickness. In addition, the M-H loop also shows an enhancement in magnetization, which is considered to result from the induced net moments at the interface.

Keywords:

• Exchange bias
• vertical shift
• interfacial exchange coupling
• frozen spins

Additional information

Funding

This work was supported by the Scientific Research Program of Tianjin Municipal Commission of Education (grant no. 2014KJ240).