Proximity effects between 2D materials and ferroelectrics

For their atomic thinness and exceptional electronic properties, 2D materials like graphene and transition metal dichalcogenides (TMD) are promising materials to build new compact and energy efficient electronic and spintronic devices. A key property of those materials is their two dimensional character which makes them highly sensitive to their environment. Thus, it offers the key opportunity to tune their electronic properties by proximity effects when the 2D material is put in contact with another functional material. In particular, the non-volatile electric field generated by a ferroelectric film will strongly affect the electronic properties of a 2D material in proximity. We could recently demonstrate a giant effect on the electronic structure of WSe2, a 2D semiconductor, in contact with BiFeO3, a well-known ferroelectric material. In spintronics, the application of an electric field to modify the spin-orbit coupling or ferromagnetic properties would represent a real breakthrough for the development of ultralow power consumption magnetic memories. Though it is almost impossible with bulk materials used today in spintronic devices, it is feasible with 2D materials in proximity with a ferroelectric material. During this thesis, our goal is to study the proximity effect between a 2D material and a ferroelectric material. More specifically, we will investigate the modification of spin-orbit coupling in PtSe2 and the modification of ferromagnetic properties in CrxTe2 by proximity effects with a ferroelectric material (BiFeO3 or LiNbO3). We also plan to extend this work to 2D ferroelectric materials and 2D ferromagnetic semiconductors in which electric field effects will be exalted. For this purpose, the 2D spintronics team of Spintec has developed a unique platform to grow 2D materials on large areas by molecular beam epitaxy as well as a method to transfer them on ferroelectric materials. This double competency is unique worldwide.

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