报告题目：Pressure-induced Structural Modulated Optical and Transporting Behaviors of 2D Materials

报 告 人：朱金龙

报告时间：2022年1月15日下午14:00

报告地点：腾讯会议 831386532

报告摘要：

Researchers show great interests in two-dimensional crystals recently, as their thickness-dependent electronic and optical properties. Compared with other tuning methods, there are no additional impurities introduced by hydrostatic pressure, thereby it is a pure and clean approach. The unique electronic structure and crystal structure driven by external pressure in transition metal tellurides (TMTs) can host unconventional quantum states.. This talk including three parts: 1) As the enforcement of layer interaction, an electronic and a crystal phase transition were revealed at ~5 GPa and ~16 GPa, respectively in bilayer MoS2, while no phase transition in monolayer. The electronic phase transition at ~5 GPa is supposed to be a direct interband changing to an indirect Λ-K interband transition, and the new structure shown at ~16 GPa is not metallized and supposed to be a transformation from stacking faults due to layer sliding like 2Hc to 2Ha; 2) Due to the proper excess V atoms into VSe2 layers, we observed pressure-induced high intensity signal of CDW increasing to room temperature around 7.6-9.1 GPa in V1.13Se2. The phase transitions of room temperature are from a metal state with P-3m1 structure and the higher c/a ratio at P < 7.6 GPa, to a CDW state with P-3m1 structure and the lower c/a ratio at 9.1 GPa < P < 14.6 GPa, and finally to another metal state with C2/m structure at P > 16 GPa; 3) Discovery of pressure-induced phase transition at ~ 2 GPa, and dome-shaped superconducting phase in van de Waals layered NbIrTe4. The highest Tc was ~5.8 K at pressure of ~16 GPa, where the interlayered Te-Te covalent bond formed simultaneously derived from the synchrotron diffraction data. Strikingly, we found an anisotropic transport in the vicinity of the superconducting state, suggesting the emergence of a “stripe”-like phase. The dome-shaped superconducting phase and anisotropic transport are possibly due to the spatially modulated interlayer Josephson coupling strength.

报告人简介：

Dr. Jinlong Zhu graduated from Institute of Physics, Chinese Academy of Sciences at 2009, and then has 3-years postdoc experience at LANSCE, Los Alamos National Lab, and 3-years postdoc experience at HPSEC, University of Nevada Las Vegas, and worked at HPSTAR as staff scientist thereafter, and currently is a tenured associate professor at Physics Department, Southern University of Science and Technology. His background is high pressure physics. By using synchrotron X-ray and neutron large facilities, his research topics include effect of pressure on quantum matters, such as Mott insulator, topological insulator and, superconductor, kinetic and dynamic studies of natural clathrate hydrates and, high-pressure synthesis of unconventional non-stoichiometric compounds and their property characterization. Dr. Jinlong Zhu totally published ~130 peer-reviewed scientific papers, and his citations are ~3000.

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