Alexei Grouverman
Dept of Physics and Astronomy
University of Nebraska-Lincoln

Electromechanical Behavior and Electronic Properties of Complex Oxide Heterostructures and Hybrid 2D Ferroelectric Devices

Location: EB1 Room 1011

Friday, October 16th 2015 - 11:00 am

Over the last decade, there have been tremendous developments in the fields of ferroelectric (FE) oxides and two-dimensional (2D) electronic materials. The revival of the first group stemmed from the recent advances in synthesis and characterization of the complex oxide materials along with predictive modeling of ferroelectricity at the nanoscale, which lead to discovery of a breadth of novel phenomena. The second group burst into the limelight with the discovery of the unusual physical properties of graphene followed by demonstration of an extended family of 2D materials with the unique physical and chemical characteristics that cannot be found in their three-dimensional counterparts. The variability of the electronic properties of 2D materials and ferroelectrics offers a wealth of fundamentally important physical phenomena and exciting technological opportunities for the hybrid 2D-FE heterostructures comprising these materials. Among particularly promising aspects of these heterostructures is the electronic transport intricately coupled and enabled by careful control of ferroelectric polarization, which allows realization of non-conventional devices with enhanced functional characteristics.

In this presentation, I will discuss implementation of the hybrid 2D-FE electronic devices that exhibit polarization-controlled non-volatile modulation of the resistive behavior. While many 2D materials can be considered in conjunction with FE materials, this talk primarily focuses on the use of graphene and transition metal dichalcogenide MoS2. Specifically, it will be shown how polarization reversal can modulate (1) the in-plane transport of the interfacial conducting channel in the FE field effect devices, and (2) the perpendicular-to-plane tunneling conductance in the FE tunnel junction devices. The role of the interface engineering in controlling the functional properties of these devices will be discussed as well. Finally, a new paradigm for voltage-free tuning of the interface conductance through mechanical stress will be presented. It will be shown that the underlying mechanism of this effect is the flexoelectric coupling between the switchable electromechanical behavior of the complex oxide materials and their electronic transport properties.

North Carolina State University