Ultrafast Switching of the Electric Polarization and Magnetic Chirality in ${\mathrm{BiFeO}}_3$ by an Electric Field

Using a first-principles-based effective Hamiltonian within molecular dynamics simulations, we discover that applying an electric field that is opposite to the initial direction of the polarization results in a switching of both the polarization and the magnetic chirality vector of multiferroic ${\mathrm{BiFeO}}_3$ at an ultrafast pace (namely, of the order of picoseconds). We discuss the origin of such a double ultrafast switching, which is found to involve original intermediate magnetic states and may hold promise for designing various devices.

Figure 1

Time evolution of (a) the supercell average of the local modes and of (b) the antiferrodistortive vector in BFO bulks under a dc electric field oriented along the [$\overline{1}\overline{1}\overline{1}$] pseudocubic direction.

Figure 2

Same as Fig. 1 but for (a) the magnetic chirality vector and (b) the magnitude of the $G$-type AFM vector.

Figure 3

Magnetic dipolar configurations along a specific [$\overline{1}01$] line joining Fe ions for some specific times. (a)–(e) Times of 0, 100, 350, 1000, and 3000 fs, respectively.

Figure 4

Schematization of the proposed four-state memory.