Electric-field Induced Reversible Switching of the Magnetic Easy-axis in Co/BiFeO3/SrRuO3/SrTiO3 Heterostructures

TL;DR

This study demonstrates reversible electric-field control of the magnetic easy-axis in Co/BiFeO3 heterostructures on SrTiO3, enabling low-power, non-volatile magnetoelectronic devices with potential integration on silicon wafers.

Contribution

It presents the first demonstration of electric-field induced reversible switching of magnetic easy-axis in Co/BiFeO3 heterostructures on SrTiO3 substrates at room temperature.

Findings

Reversible 45° switching of magnetic easy-axis with voltage pulses.

Hysteretic coercivity behavior as a function of voltage.

Neutron diffraction measurement of antiferromagnetic domain canting angle.

Abstract

Electric-field (E-field) control of magnetism enabled by multiferroics has the potential to revolutionize the landscape of present memory devices plagued with high energy dissipation. To date, this E-field controlled multiferroic scheme at room temperature has only been demonstrated using BiFeO3 (BFO) films grown on DyScO3 (refs 1 and 2), a unique and expensive substrate, which gives rise to a particular ferroelectric domain pattern in BFO. Here, we demonstrate reversible E-field-induced switching of the magnetic state of the Co layer in Co/BFO (001) thin film heterostructures fabricated on SrTiO3 substrates. The angular dependence of the coercivity and the remanent magnetization of the Co layer indicates that its easy axis reversibly switches by 45{\deg} back and forth between the (100) and the (110) crystallographic directions of SrTiO3 as a result of alternating application of positive and negative voltage pulses on BFO. The coercivity of the Co layer exhibits a hysteretic behavior between two states as a function of voltage. To explain the observation, we have also measured the exact canting angle of the antiferromagnetic G-type domain in BFO films for the first time using neutron diffraction. These results suggest a pathway to integrating BFO-based devices on Si wafers for implementing low power consumption and non-volatile magnetoelectronic devices.