arXiv subjects

Xian-Kui Wei

Publications and source records attributed to Xian-Kui Wei.

3 recordsLinked to original sources

arXiv2023

Antiferroelectric Oxide Thin-Films: Fundamentals, Properties, and Applications

Antiferroelectrics have received blooming interests because of a wide range of potential applications in energy storage, solid-state cooling, thermal switch, transducer, actuation, and memory devices. Many of those applications are the most prospective in thin film form. The antiferroelectric ordering in thin films is highly sensitive to a rich set of factors, such as lattice strain, film thickness, surface and interface effects as well as film stoichiometry. To unlock the full potential of these materials and design high-quality thin films for functional devices, a comprehensive and systematic understanding of their behavior is essential. In conjunction with the necessary fundamental background of antiferroelectrics, we review recent progress on various antiferroelectric oxide thin films, the key parameters that trigger their phase transition and the device applications that rely on the robust responses to electric, thermal, and optical stimuli. Current challenges and future perspectives highlight new and emerging research directions in this field. It is hoped that this review can boost the development of antiferroelectric thin-film materials and device design, stimulating more researchers to explore the unknowns together.

cond-mat.mtrl-sci↗

arXiv2023

Atomic diffusion-induced polarization and superconductivity in topological insulator-based heterostructures

The proximity effect at a highly transparent interface of an s-wave superconductor (S) and a topological insulator (TI) provides a promising platform to create Majorana zero modes in artificially designed heterostructures. However, structural and chemical issues pertinent to such interfaces are poorly explored so far. Here, we report the discovery of Pd diffusion induced polarization at interfaces between superconductive Pd$_{1+x}$(Bi$_{0.4}$Te$_{0.6}$)$_2$ (xPBT, $0\le x \le 1$) and Pd-intercalated Bi$_2$Te$_3$ by using atomic-resolution scanning transmission electron microscopy. Our quantitative image analysis reveals that nanoscale lattice strain and QL polarity synergistically suppress and promote the Pd diffusion at the normal and parallel interfaces, formed between Te-Pd-Bi triple layers (TLs) and Te-Bi-Te-Bi-Te quintuple layers (QLs), respectively. Further, our first-principles calculations unveil that the superconductivity of xPBT phase and topological nature of Pd-intercalated Bi$_2$Te$_3$ phase are robust against the broken inversion symmetry. These findings point out the necessity of considering coexistence of electric polarization with superconductivity and topology in such S-TI systems.

cond-mat.mtrl-sci↗

arXiv2022

Proximity-induced superconductivity in (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ topological-insulator nanowires

When a topological insulator is made into a nanowire, the interplay between topology and size quantization gives rise to peculiar one-dimensional states whose energy dispersion can be manipulated by external fields. In the presence of proximity-induced superconductivity, these 1D states offer a tunable platform for Majorana zero modes. While the existence of such peculiar 1D states has been experimentally confirmed, the realization of robust proximity-induced superconductivity in topological-insulator nanowires remains a challenge. Here, we report the realization of superconducting topological-insulator nanowires based on (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ (BST) thin films. When two rectangular pads of palladium are deposited on a BST thin film with a separation of 100--200 nm, the BST beneath the pads is converted into a superconductor, leaving a nanowire of BST in-between. We found that the interface is epitaxial and has a high electronic transparency, leading to a robust superconductivity induced in the BST nanowire. Due to its suitable geometry for gate-tuning, this platform is promising for future studies of Majorana zero modes.

cond-mat.mes-hall↗