Interface design for the transport properties in asymmetric two-dimensional van der Waals multiferroic tunnel junctions

Abstract

Multiferroic tunnel junctions (MFTJs) composed of ferroelectricity and ferromagnetism have attractive prospects in memory and computing device applications due to their low power consumption and nonvolatile switching. However, achieving both spin filter effect (SFE) and excellent tunnel electroresistance (TER) effect in two-dimensional (2D) van der Waals (vdW) MFTJs still remain challenging. Herein, using first-principles calculations, we investigate interface design for electronic and transport properties of asymmetric 2D vdW MFTJs that consist of CrI 3 , graphene, and ferroelectric Sc 2 CO 2 (containing Sc– P↑ and Sc– P↓ states). We find that such CrI 3/Sc– P↑/graphene MFTJs exhibit p -type Ohmic contact for Sc– P↑/graphene and SFE for CrI 3 / Sc– P↑ due to the transformation of CrI 3 from intrinsic semiconductor to half-metal. Simultaneously, the Dirac point of graphene at the Fermi energy has a big shift about 0.95 eV with the polarization reversal, suggesting that there is a giant barrier modulation. Moreover, the huge TER ratio about 1.7′10 5 % was also discovered by transport calculations. Our results provide an avenue for the design of future 2D vdW MFTJs. • 2D CrI 3 /Sc 2 CO 2 /graphene van der Waals MFTJ shows multiple nonvolatile resistance and high ratio of tunneling electroresistance. • Two heterointerfaces in CrI 3 / Sc– P↑/graphene exhibit Ohmic contact, while those in CrI 3 / Sc– P↓/graphene are Schottky contact. • Spin filter effect can take place in CrI 3 / Sc– P↑/graphene due to the transformation of CrI 3 from intrinsic semiconductor to half-metal. • Dirac point of graphene at the Fermi energy has a big shift about 0.95 eV with the polarization reversal.