Imaging 2D Wigner solid and its Quantum Melting with Local Disorders.
Two-dimensional strongly interacting electrons crystalize into a solid phase known as the Wigner crystal at low densities and form a Fermi liquid at high densities. At intermediate densities, the two-dimensional solid evolves into a strongly correlated liquid phase around a critical density. We observe this quantum melting of a disordered Wigner solid in bilayer MoSe2 using a non-invasive scanning tunneling microscopy imaging technique. At low densities, the Wigner solid forms nanocrystalline domains pinned by local disorder. It exhibits a quantum densification behavior with increased densities in the solid phase. Above a threshold density, the Wigner solid melts locally and enters a mixed phase where solid and liquid regions coexist. The liquid regions expand and form a percolation network at even higher densities.
Ziyu Xiang is currently a 5th-year Applied Science & Technology PhD candidate in Prof. Feng Wang's group. His research work mainly focuses on experimental condensed matter physics, particularly the behavior of strongly correlated electrons in 2D heterostructures, by applying scanning tunneling microscope (STM). He enjoys climbing and skiing.
Emissive Chalcogenide Perovskite Nanowires
Efficient and stable one-dimensional semiconductor nanowires are critical for the development of next-generation on-chip optoelectronics. We developed a synthetic approach to produce high-quality nanowires based on chalcogenide perovskite via a vapor phase reaction inside a sealed ampoule. An epitaxial vapor-phase growth mechanism is proposed. The nanowires are shown to be single-crystalline and highly structurally stable. Red and green photoluminescence (PL) is observed from BaZrS3 and SrHfS3 nanowires, respectively. PL lifetime is on the timescale of nanoseconds, indicating good nanowire sample quality with a promising potential for optoelectronic applications.
Yuxin Jiang is currently a 4th-year Chemistry PhD candidate in Prof. Peidong Yang's group. Her research work focuses on synthesis of 1D semiconductor nanostructures and studies of their optoelectronic properties. She enjoys watercolor painting and jigsaw puzzles.