Mechanical force involved multiple fields switching of both local ferroelectric and magnetic domain in a Bi5Ti3FeO15 thin film

摘要

Multiferroics have received intense attention due to their great applicationpotential in multi-state information storage devices and new types of sensors.Coupling among ferroic orders such as ferroelectricity, (anti-)ferromagnetism,ferroelasticity, etc. will enable dynamic interaction between these orderingparameters. Direct visualization of such coupling behaviour in single phasemultiferroic materials is highly desirable for both applications andfundamental study. Manipulation of both ferroelectric and magnetic domains ofBi5Ti3FeO15 thin film using electric field and external mechanical force isreported, which confirms the magnetoelectric coupling in Bi5Ti3FeO15, indicatesthe electric and magnetic orders are coupled through ferroelasticity. Due tothe anisotropic relaxation of ferroelastic strain, the back-switching ofout-of-plane electric domains is not as obvious as in-plane. An inevitabledestabilization of the coupling between elastic and magnetic ordering happensbecause of the elastic strain relaxation, which result in a subsequent decay ofmagnetic domain switching. Mechanical force applied on the surface ofBi5Ti3FeO15 film generates by an AFM tip will effectively drive a transition ofthe local ferroelastic strain state, reverse both the polarization andmagnetization in a way similar to an electric field. Current work provides aframework for exploring cross-coupling among multiple orders and potential fordeveloping novel nanoscale functional devices.