Recently, Guo Yao's research group at the School of Physics at Beijing Institute of Technology published a research paper titled "Zero-dimensional Van der Waals Interface Ferroelectric Effect" in Nature Communications (paper link: https://www.nature.com/articles/s41467 -023-41045-8). This work breaks the size limitation of traditional ferroelectric effects, and for the first time confirms the extremely small-scale zero-dimensional solid-state ferroelectric effect with exact experimental evidence and theoretical calculations. This research result shows that the van der Waals interface slip ferroelectric effect has important advantages in future high-density information storage and is of great significance to the size reduction of ferroelectric memory.

Ferroelectric effect dimensions and types

The ferroelectric effect is an important physical phenomenon discovered by Joseph Valasek a hundred years ago. The traditional ferroelectric effect is limited by the size effect - when the size of the ferroelectric material is reduced to a certain extent, the significant impact of the depolarization field will cause the ferroelectric material to lose polarization. This size effect greatly limits the application of ferroelectric materials in high-density memory devices. In recent years, a ferroelectric effect that does not depend on ion lattice changes but is generated by van der Waals interface slip has attracted widespread attention. However, previous research on the slip ferroelectric effect has mainly focused on two-dimensional and three-dimensional material systems. Further size reduction of the slip ferroelectric effect is an important puzzle piece for the entire ferroelectric effect research framework. In this regard, Guo Yao's research group used nanotubes to construct zero-dimensional van der Waals interfaces and devices based on the original work on the slip ferroelectric effect, and observed the resistive switching and hysteresis phenomena of ferroelectric diodes. Through further experiments and theoretical calculations, it was verified that the electrical behavior of the ferroelectric diode is due to lattice slip at the zero-dimensional van der Waals interface, allowing the device to produce resistance changes that can be used for information storage and can produce programmable photovoltaic responses over nearly the entire visible wavelength range.

Mechanism verification and photovoltaic response of zero-dimensional slip ferroelectric effect

Beijing Institute of Technology is the first unit of this work. The cooperating units include Alla Zak's research group at the Holon Institute of Technology in Israel and Reshef Tenne's research group at the Weizmann Institute of Science. This work also received relevant support from Peking University. This work was funded by the National Natural Science Foundation of China, the Strategic Priority Science and Technology Project of the Chinese Academy of Sciences, the China Postdoctoral Science Foundation, and the Israel Science Foundation. Niu Yue, a master's student at Beijing Institute of Technology, and Li Lei, a postdoctoral fellow, are the co-first authors of the paper. Professor Yao Yugui provided strong support in first-principles calculations for this work.