Electric-Field-Induced Magnetization Reversal in a Ferromagnet-Multiferroic Heterostructure

Abstract

A reversal of magnetization requiring only the application of an electric field can lead to low-power spintronic devices by eliminating conventional magnetic switching methods. Here we show a nonvolatile, room temperature magnetization reversal determined by an electric field in a ferromagnet-multiferroic system. The effect is reversible and mediated by an interfacial magnetic coupling dictated by the multiferroic. Such electric-field control of a magnetoelectric device demonstrates an avenue for next-generation, low-energy consumption spintronics.

Non-volatile electrically-driven repeatable magnetization reversal with no applied magnetic field

“…3). In contrast to previous reports, we require no externally applied magnetic field 12,18,19,[21][22][23] . The resulting model permits nominally full reversal, and was inspired by recognizing that an electrically driven strain-mediated fast and temporary reduction of uniaxial magnetic anisotropy can trigger precessional reversal of magnetization in the presence of a fixed transverse magnetic field.…”

“…standard magnetic hysteresis loops. While we were completing this manuscript, anisotropic magnetoresistance data were presented 23 as evidence of electrically driven magnetic reversal in an island of Co 0.90 Fe 0.10 on BiFeO 3 , but this indirect measurement required an applied magnetic field whose possible unintended role in magnetization reversal cannot be ruled out, especially as the measurement field was similar to the coercive field. Therefore, magnetization reversal under purely electrical control with no applied magnetic field remains outstanding.…”

“…A magnetic field is also needed, but in contrast with previous schemes 12,18,19,[21][22][23] , no changes in its direction or magnitude are required for repeatable switching. Our model based on a single macrospin may be exploited for high-density data storage with suitably designed nanomagnets, where the temporary reduction of anisotropy, and thus thermal stability, can be tolerated as the switching process is fast.…”

Voltage-controlled low-energy switching of nanomagnets through Ruderman-Kittel-Kasuya-Yosida interactions for magnetoelectric device applications

“…The energy required for switching Es is that required for charging and discharging the gate capacitors. Here we take that to be = 2 (11) as for CMOS, where Vg is the gate voltage and Cg is the total gate capacitance. Ignoring parasitic capacitances, we approximate the latter as the series combination of oxide capacitance and TI quantum capacitance.…”

“…However, some of this advantage may be lost for nanoscale magnets due to the limited length of the transport path beneath the magnet, and, particularly for TIs, current shunting to a metallic magnet [10]. Voltage-aided or induced switching of nanomagnets also is being considered to reduce or eliminate the current requirement for still more power-efficient switching [11]. However, such methods rely on voltage-induced changes in the magnet's easy axis orientation and strength, requiring precise fabrication to achieve a nominal magnetic anisotropy on the boundary between vertical and in-plane orientations, and applied voltages that still would be substantial compared to those employed for CMOS logic [12].…”