Integration of BiFeO3/La0.7Sr0.3MnO3 heterostructures with III–V semiconductors for low-power non-volatile memory and multiferroic field effect transistors

Abstract

We report on the use of SrTiO₃ films on GaAs(001) substrates grown by molecular beam epitaxy (MBE) as intermediate buffer layers for the heteroepitaxial growth of ferromagnetic La_0.7Sr_0.3MnO₃ (LSMO) and room temperature multiferroic (ferroelectric/antiferromagnetic) BiFeO₃ (BFO) thin films using the pulsed laser deposition technique. The exchange bias coupling effect in the BFO/LSMO heterostructure has been investigated. The magnetization measurements with field cooling exhibit a surprising increment in the magnetic moment with enhanced magnetic hysteresis squareness. This we believe is the consequence of exchange interactions between the antiferromagnetic BFO and the ferromagnetic LSMO at the interface. The integration of BFO materials with LSMO on GaAs substrates facilitated the demonstration of resistive switching based non-volatile memory (NVM) devices which can be faster with lower energy consumption compared to present commercial technologies. Ferroelectric switching observations using piezoresponse force microscopy show polarization switching demonstrating its potential for read–write operation in NVM devices. The ferroelectric and electrical characterization exhibits strong resistive switching with low set/reset voltages. Furthermore, we demonstrate a prototypical epitaxial field effect transistor based on multiferroic BFO as the gate dielectric and ferromagnetic LSMO as the conducting channel. The device exhibits a modulation in channel conductance with a high ON/OFF ratio. This work also demonstrates the first step towards the development of magneto-electronic devices integrated with a compound semiconductor.