Abstract
Magnetoelectric (ME) coupling in materials offer tremendous advantages in device functionality enabling technologies including advanced electronic memory, combining electronic speed, and efficiency with magnetic robustness. However, low cost polycrystalline ME materials are excluded from most commercial applications, operating only at cryogenic temperatures, impractically large electric/magnetic fields, or with low ME coefficients (1-100 mV/cm Oe). Despite this, the technological potential of single compound ME coupling has continued to drive research into multiferroics over the last two decades. Here we show that by manipulating the large induced atomic strain within the polycrystalline, room temperature multiferroic compound 0.7BiFeO3–0.3PbTiO3, we can induce a reversible, piezoelectric strain controlled ME effect. Employing an in situ neutron diffraction experiment, we have demonstrated that this piezomagnetoelectric effect manifests with an applied electric field >8 kV/mm at the onset of piezoelectric strain, engineered in to the compound by crystallographic phase mixing. This produces a remarkable intrinsic ME coefficient of 1276 mV/cm Oe, due to a strain driven modification to the oxygen sub-lattice, inducing an increase in magnetic moment per Fe3+ ion of +0.142 μB. This work provides a framework for investigations into strain engineered nanostructures to realize low-cost ME devices designed from the atoms up, as well as contributing to the deeper understanding of single phase ME coupling mechanisms.
Highlights
Modifications of the (200)R, {110}R, and {111}R peaks, as a function of applied electric field parallel to the neutron beam, show increasing lattice shift and integrated intensities for 0 ≤ E ≤ 11 kV/mm (Figure 2)
Particular attention has been given to bismuth ferrite (BiFeO3)[1,2] pertaining to its room temperature ferroelectric (FE) (TC = 1100 K)[2] and G-type antiferromagnetic (AFM) (TN ∼ 643 K)[2] properties, where the linear ME effect[2] is prohibited in the bulk due to an incommensurate magnetic structure[3] inherent to the rhombohedrally distorted (R3c) perovskite crystal structure
The BFPT compound remains rhombohedral from 1 ≥ x > 0.7, whereas for x < 0.7 the equilibrium crystal structure is tetragonal
Summary
Modifications of the (200)R, {110}R, and {111}R peaks, as a function of applied electric field parallel to the neutron beam, show increasing lattice shift and integrated intensities for 0 ≤ E ≤ 11 kV/mm (Figure 2). The neutron diffraction data collected show a polycrystalline sample of x = 0.7 BFPT undergoes three separate field-dependent atomic re-ordering mechanisms as a function of applied electric field which result in a reversible piezomagnetoelectric response.
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