Room-Temperature\nMagnetic Switching of the Electric\nPolarization in Ferroelectric Nanopillars

Abstract

Magnetoelectric\nlayers with a strong coupling between ferroelectricity\nand ferromagnetism offer attractive opportunities for the design of\nnew device architectures such as dual-channel memory and multiresponsive\nsensors and actuators. However, materials in which a magnetic field\ncan switch an electric polarization are extremely rare, work most\noften only at very low temperatures, and/or comprise complex materials\ndifficult to integrate. Here, we show that magnetostriction and flexoelectricity\ncan be harnessed to strongly couple electric polarization and magnetism\nin a regularly nanopatterned magnetic metal/ferroelectric polymer\nlayer, to the point that full reversal of the electric polarization\ncan occur at room temperature by the sole application of a magnetic\nfield. Experiments supported by finite element simulations demonstrate\nthat magnetostriction produces large strain gradients at the base\nof the ferroelectric nanopillars in the magnetoelectric hybrid layer,\ntranslating by flexoelectricity into equivalent electric fields larger\nthan the coercive field of the ferroelectric polymer. Our study shows\nthat flexoelectricity can be advantageously used to create a very\nstrong magnetoelectric coupling in a nanopatterned hybrid layer.