Manipulating the exchange bias effect of Pb(Zr_(0.52)Ti_(0.48))O_3/CoFe_2O_4/NiO heterostructural films by electric fields

摘要

The Pb(Zr_(0.52)Ti_(0.48))O_3/CoFe_2O_4/NiO heterostructural films with exchange bias (EB) effect have been prepared on Pt/Ti/SiO_2/Si wafers using a sol-gel process, and reversible manipulation of EB effect by electric fields has been realized. Compared with the exchange bias field (H_(eb) = -75 Oe) at as-grown state, the modulation gain of H_(eb) by electric fields can reach 83% (H_(eb) = -12.5 Oe) in the case of +5.0 V and 283% (H_(eb) = -287.5 Oe) in the case of -5.0 V, respectively. Moreover, such electrically tunable EB effect is repeatable and has good endurance and retention. Through analyzing the energy band structures in different electric treatment states, we discuss the mechanism of such electric-field-tunable EB effect. Two factors, i.e., the filling (or releasing) of electrons into (or from) the defect levels produced by oxygen vacancies at positive (or negative) electric voltages, and the redistribution of electrons due to the ferroelectric polarization, both of which give rise to the variation of the strength of exchange interaction in the CFO layer, have been revealed to be responsible for the electric modulation of EB effect. This work provides a promising avenue for electrically manipulating the EB effect and developing high-performance memory and storage devices with low power consumption.