Synergetic Electronic and Ionic Contributions to Electroresistance in Ferroelectric Capacitors

Advanced use of ferroelectric capacitors in data storage and computing relies on the control of their electrical resistance (electroresistance, ER) by the change of the electrostatic potential profile across the capacitor occurring upon electric field-driven polarization switching. Here it is reported the observation that BaTiO3-based capacitors, sandwiched between Pt and La2/3Sr1/3MnO3 electrodes, display a large ER, whose magnitude (near 10(4)% at room temperature) and sign (ER > 0, ER < 0) are determined by the writing pulse duration and temperature. Temperature-dependent measurements have been instrumental to obtain evidence of the presence of a thermally activated process coexisting with the electronic changes produced by ferroelectric polarization switching, both contributing to ER. Detailed analysis allows concluding that the thermally activated process can be attributed to field-assisted ionic motion. It is argued that the relative balance between purely electronic and ionic diffusion processes modulate the height of the interfacial Schottky barriers and, consequently, are responsible for the observed variations of magnitude and sign of ER.