Ferroelectric Ultra-Thin Films and Tunnel Junctions: Size and Boundary Condition Effects

Dr. Somnath Kale
SPEC, CEA, CNRS, Université Paris-Saclay, France and
Department of Physical Sciences, Indian Institute of Science Education and Research, Berhampur, India

Ferroelectricity—an intrinsic property of certain dielectric materials—continues to draw attention due to the discovery of new phenomena in nanostructures featuring ferroelectric order parameters. Ferroelectric materials, known for their electrically reconfigurable spontaneous polarization, have been extensively employed in many possible commercial applications, ranging from non-volatile memories and field-effect transistors to recently proposed tunnel junctions and neuromorphic computing. At present, owing to the ever-increasing demand for gadgets with smaller package sizes and enhanced functionalities, ferroelectric ultrathin films are being intensively investigated in academia and industry for high-density and low-power nanoscale electronics. Given that the performance and microscopic functionalities of future nanodevices are inevitably linked to the ferroelectric properties of ultrathin films, the comprehension of factors affecting nanoscale ferroelectricity is crucial.

In this talk, I will discuss the effects of ferroelectric size as well as electrical and mechanical boundary conditions on ferroelectricity in ultrathin films and their potential applications including tunnel junctions. Commencing with thicker films, we explored how thickness downscaling affects the statics and dynamics of domains and domain walls. We have shown that the change in the dimensionality of the ferroelectric domain walls with the reduction in film thickness, perhaps mediated by the compressive strain along with the long-range strain-dipolar interactions. Further meticulous investigations in the ultrathin regime, where the films are fully strained, revealed the abundance of one-dimensional domain walls attributable to the reduced physical dimension of the system. When these ultrathin films are integrated between two electrodes to form ferroelectric tunnel junctions (FTJs), the electrical boundary conditions—arising from both the electrodes and their interfaces—play a critical role in determining device functionality. Our investigations into electrode-dependent electroresistance behavior, followed by polarization switching dynamics, revealed the significant impact of underlying switching mechanisms and depolarization effects in shaping tunneling electroresistance (TER) behavior. These findings highlight the crucial role of thickness, strain, and electrodes, offering valuable insights for the design and development of future ferroelectric devices.

CRC 1461: Neurotronics
Colloquium: 22-May-2025_36, Thursday, 02:00 pm to 03:00 pm (CET)

Link to the zoom meeting

Invited by Hermann Kohlstedt
Kiel University, Faculty of Engineering, Nanoelectronics

Download the announcement here.