Polytype switching by super-lubricant van der Waals cavity arrays

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Field-effect device performance is crucial for the chip industry.
• Non-volatile multiferroic transistors controlling atomic movements are highly desired.
• Previous ferroelectric switching methods were limited by large domains and pre-existing dislocations.

Purpose of the Study:

• To report robust electric switching of single-domain polytypes in nanometre-scale islands.
• To demonstrate a new concept for 'slidetronics' device applications.
• To enable the design of novel electronic components like multiferroic transistors and memory cells.

Main Methods:

• Etching cavities into a layered spacer and encapsulating with functional flakes to create nanometre-scale islands.
• Utilizing super-lubricant van der Waals (vdW) arrays to form islands of commensurate and metastable polytype configurations.
• Imaging polarization to observe boundary strip dynamics and ferroelectric hysteresis loops, and applying mechanical stress for control.

Main Results:

• Achieved robust electric switching of single-domain polytypes in nanometre-scale islands.
• Observed nucleation and annihilation of boundary strips and geometry-adaptable ferroelectric hysteresis loops.
• Demonstrated control over boundary strip position, twist angles, and polar domain patterns using mechanical stress.

Conclusions:

• The super-lubricant arrays of polytype (SLAP) concept enables new 'slidetronics' device applications.
• This approach facilitates the development of elastic-coupled neuromorphic memory cells and non-volatile multiferroic tunnelling transistors.
• Programmable responses can be achieved by designing island and array geometries.