自旋轨道电子设备、关联电子体系、超大质量黑洞、单层MoSe₂、天文X射线偏振测量 | 本周物理讲座

2关于单层MoSe₂中一维镜面畴界之电子态的空间调制问题

报告人：谢茂海，香港大学物理系

时间：3月16日(周二) 15:00

单位：合肥微尺度物质科学国家研究中心、 国际功能材料量子设计中心（ICQD）

参会方式：蔻享直播

会议链接：https://www.koushare.com/lives/room/698029

摘要：

大量实验表明，在外延的MoSe₂单层薄膜中会自发形成大量的镜面畴界，而该畴界表现为一维金属，其低能激发态呈现出一系列奇特物性。其中一个比较明显的实验特征为空间电荷周期调制，其起源在文献中已提出不同的建议，如量子限制效应、电荷密度波、Moiré效应、Luttinger液体等等。我们通过选择不同衬底进行MoSe₂薄膜外延生长、通过调节生长条件控制MoSe₂薄膜中镜面畴界的长度，并对其进行细致的低温扫描隧穿电镜及谱的测量，从而确立一维畴界之电子金属态的量子限制效应和Friedel震荡是实验上观测到的空间电荷调制的主要原因，而且，在石墨或石墨烯上的MoSe₂畴界，其低能激发态与Luttinger液体行为一致，而在金衬底上的同类畴界更像费米液体。 

报告人简介： 

谢茂海教授现就职于香港大学物理系。他1985年毕业于天津大学电子工程系，1988年获得中科院半导体所硕士学位，1994年伦敦大学帝国理工学院博士学位。经历了2年多于伦敦大学帝国理工学院的博士后研究后，于1997年加入香港大学物理系，先后任职为助理教授、副教授、教授，并于2017年1月至2019年12月任系主任。他也曾任香港物理学会副主席、主席。谢教授的科研兴趣为材料于表面物理，尤其是薄膜材料的分子束外延生长及其表面原子结构和电子性质进行电子衍射、扫描隧穿显微镜、及光电子能谱的表征。近年来，他着重于二维材料(如MoSe₂, WSe₂, MoTe₂等)的外延生长和性质研究，并已发表科技论文150多篇。

3Galaxy spins from the primordial perturbations

报告人：于浩然，厦门大学

时间：3月16日(周二) 16:00

单位：中国科学技术大学天文学系

参会方式：蔻享直播

会议链接：https://www.koushare.com/lives/room/477089

摘要：

I will discuss the galaxy angular momenta — their origin, observation, prediction, and they as a potential probe of the primordial Universe. In the current and upcoming galaxy surveys we have focused on galaxies’ positions and velocities. Galaxies also have rotations and we can use these informations to learn more about the Universe. In Lagrangian space the protohalo spins are well described by the tidal torque theory, and numerical simulations have given a general picture of spin conservation over galaxy formation. We have verified the correlation between observed galaxy spins and cosmic initial conditions (density mode reconstruction by ELUCID). We have also proposed the potential detection of neutrino mass, possible parity violation via galaxy spins in Lagrangian space.

报告人简介：

4关联电子体系中竞争电子序的高压调控

报告人：程金光，中国科学院物理研究所

时间：3月17日(周三) 19:00

单位：蔻享学术

参会方式：蔻享直播

会议链接：https://www.koushare.com/lives/room/036648

摘要：

施加物理压力是改变温度和磁场之外调控凝聚态物质状态的重要手段之一。通过原位高压下的物性测量，尤其是将高压与低温和磁场等综合极端条件相结合，可以调控研究强关联电子体系中丰富奇特的量子有序态和关联演生现象。高压调控原则上不引入晶格无序和额外载流子，而且能够连续变化，被认为是一种“干净且精细“的调控手段。在本报告中，我将简要介绍高压调控的意义和目前常用的高压物性测量技术，然后重点介绍我们最近利用高压调控关联电子体系中竞争电子序的研究进展，主要包括：在尖晶石HgCr₂Se₄中通过高压和磁场的联合调控实现了铁磁金属基态到反铁磁绝缘态的转变和伴随的巨磁阻效应；在最近发现的笼目金属CsV₃Sb₅中通过高压调控电荷密度波实现了双拱形超导相图和超导转变温度的提升。

报告人简介：

程金光，中科院物理所研究员。2003和2005年在哈工大物理系取得本科和硕士学位，2010年在美国德克萨斯大学奥斯汀分校获博士学位并接着进行了两年博士后研究。2012-2014年在日本东京大学物性研究所做JSPS博士后。主要研究方向是高压极端条件下的新材料和奇异物性研究。荣获中科院卢嘉锡青年人才奖和马丁伍德爵士中国物理科学奖。2020年获得国家杰出青年科学基金资助。迄今在PRL、JACS、Nature Comm.和PNAS等期刊上发表论文190余篇。

5The Impact of Supermassive Black Holes on Galaxy Formation and Fundamental Physics

报告人：Prof. Luis Ho, Peking University

时间：3月17日(周三) 16:00

单位：上海交通大学

参会方式：ZOOM

会议链接：https://zoom.com.cn/j/67297413270 

PIN: 938962

摘要：

The centers of all massive galaxies contain supermassive black holes weighing millions to tens of billions times the mass of the Sun.  Recent observations reveal that even a significant fraction of low-mass galaxies contain smaller intermediate-mass black holes, which give new insights into the birth of supermassive black holes and offer predictions for the next generation of gravitational wave experiments.  Accretion of matter by central black holes power energetic phenomena such as quasars and various forms of active galactic nuclei.  The energy and momentum released by accretion, in turn, may strongly influence the lifecycle of galaxies.  I will summarize the critical observations over the past 20 years that have led to the discovery of the widespread existence of black holes in galaxies, which is among one of the most important developments in modern astrophysics.

报告人简介：

Prior to joining KIAA, Luis Ho was a Staff Astronomer for 15 years at the Observatories of the Carnegie Institution for Science.  His research covers a wide range of different, but interrelated areas, using all available observational techniques spanning from radio to X-ray energies.  He actively uses ground-based telescopes and space-based astronomical satellites. The main topics of his research, published in over 350 refereed papers,  include: (1) active galaxies and quasars, including the physics of emission-line regions, accretion disks, jets, and host galaxies; (2) searches for massive black holes, from star clusters to the centers of galaxies; (3) coevolution of black holes and galaxies, black hole scaling relations, and AGN feedback; (4) galaxy structure and the origin of the Hubble sequence; (5) extragalactic star formation; and (6) the interstellar medium.  

6Reopening the window of astronomical X-ray polarimetry with PolarLight

报告人：Hua Feng，Tsinghua University

时间：3月18日（周四）16:00

单位：北京大学物理学院

地点：KIAA-auditorium

摘要：

Polarimetry in the X-ray band is argued to be a powerful and sometimes unique tool in diagnosing the magnetic field, geometry and emission mechanism in astrophysics. PolarLight,which is a miniature X-ray polarimeter onboard a CubeSat, is the first dedicated astronomical X-ray polarimeter since the OSO-8 experiment in 1970s. It was launched into a low-Earth orbit in October 2018 and is still working in space. In this talk, I will introduce the PoarLight space program and the science results that have been obtained with it.

报告人简介：

Hua Feng is a professor in the Department of Astronomy at Tsinghua University. He received his bachelor’s and PhD degrees at Tsinghua University, and was a postdoc and subsequently an assistant research scientist at the University of Iowa before he joined the faculty at Tsinghua. He conducts research in high energy astrophysics, focusing on observational X-ray astronomy and instrumentation for future space programs. He led the launch and operation of Polar Light, which is the first dedicated soft X-ray polarimeter in space since the OSO-8 experiment in the 1970s. He is also interested in X-ray and optical observations of accreting compact objects, trying to reveal observational signatures associated with supercritical accretion. In recent years, he is particularly interested in understanding the outflow driven by supercritical accretion.