Quantum Matter Seminar: Pressure-induced charge orders and their responses to the magnetism and superconductivity in layered materials

杨文革

北京高压科学研究中心

报告时间：2024年4月22日（周一）下午15:30

报告地点：紫金港校区段永平教学楼2号楼212报告厅

摘要：

Charge order (CO) plays an important role in materials properties, such as multiferroicity in electronic device and spintronics, competition/cooperation with superconductivity. Pressure has been used as an efficient fine-tuning tool on electronic and crystal structures, and many advances have been made over the past decates. Being a layered material, it is also interesting to unerstand how the layers interact with each other and what the role of pressure is. Advanced synchrotron technology allows the identification of the charge density wave (CDW) vectors and their evolution under pressure through single crystal diffraction method, detects the net magnetic moment field related to charge ordering under a variety of extreme conditions (high pressure, low temperature and strong megnetic field). The transition-metal dichalcogenide (TMD) systems with van der Waals heterostructures (VDWH) often exhibit CDW and superconductivity (SC). The understanding of the relationship (co-existing, competing or cooperating) between CDW and SC in the VDWH is still quite limited. It is of both technical and scientific interest to investigate the behavior of various TMD systems with different layer properties and compare them with the two-dimensional limit layered systems. In the lecture, I will focus on two systems: 1)the layered multiferroic system LuFe₂O₄, which witnesses the transformation of CDW vector from three-dimensional CO to two-dimensnional CO, accompanied by the quenching of magnetic moment; 2)the bulk 4Hb-TaSe₂ TMD consisting of alternative stacking of T-layer and H-layer with supression of CDW and enhancement SC from both layers along with the pressure induced quasi-2D to quasi-3D compression behavior. As one of the state parameters, the more functional materials and new sciences brought about by pressure will bring us great opportunities to explore one more dimension of physical science.

报告人简介：

杨文革，1995年武汉大学物理系毕业，获得凝聚态物理博士学位。1995-1997年在德国尤利希研究中心担任洪堡学者。 随后，他先后在美国卡内基梅隆大学、橡树岭国家实验室和华盛顿卡内基研究院继续其职业生涯，担任博士后、研究员和科研主管。于 2014 年回国全职加入北京高压科学研究中心 (HPSTAR)，担任研究员。目前担任中心主任。 杨博士的研究主要集中在高压科学和先进同步辐射技术在极端条件下的应用。 发表SCI论文300余篇，被引用13000余次。 近年来主要致力于新型材料的合成、表征及其在高压下的新兴性能。 他对综合极端条件（包括压力、磁场、高/低温、应变率等）下凝聚态物质（晶体、液体、非晶和准晶相）的结构变形/稳定性、相变、有序-无序特性以及相关物理性质感兴趣。