超低场核磁共振、交错磁性、奇异量子材料、全电学垂直磁矩翻转 | 本周物理讲座

报告人：王维波，中国电子科技集团公司第五十五研究所

时间：12月19日（周二）10:00

单位：中科院物理所

地点：M楼249会议室

摘要：

低温固态低噪声放大器芯片是量子计算、宇航探测等领域的核心技术之一，决定了低温系统工作的信噪比，备受国内外研究人员的关注。近年来，随着国内半导体材料外延、器件工艺等关键技术的进步，低温固态器件的的相关研究和发展取得了长足的进步。本文将半导体技术入手，从外延材料、器件工艺、模型提取、电路设计、可靠性等方面总结低温固态放大器研发存在的难点和挑战，对其中的关键技术和方法进行探讨，期望通过这些工程中存在的问题为未来低温低噪声放大器芯片的研发设计人员提供积极意义的参考。

报告人简介：

王维波，中国电子科技集团公司第五十五研究所主任设计师，研究员/博士，国家太赫兹、固态微波领域专家，江苏省“333高层次人才”。负责并完成多项重大专项、型谱、新品、预研项目和多项重点工程项目，荣获多项科研成果奖励，作为三代半导体（氮化镓）团队核心成员获得“第二届全国创新争先奖”、工信部国防科学技术奖一等奖、二等奖、三等奖、中国电子科技集团公司科学技术奖一等奖、二等奖、三等奖多项奖励。

报告人：吴俊宝，Tianjin University

时间：12月20日（周三）10:00

单位：中科院理论物理所

地点 ： 理论物理所南楼6620

摘要：

There are five consistent string theories at the perturbative level. Later, it was discovered that they are related through various dualities. There is another corner in this duality web. That is the M-theory (in the narrow sence). There are two kinds of stable branes in M-theory: M2-branes and M5-branes. Study of low energy effect theories of multi-membranes are important problem since the establishment of M-theory. In 2008, Ahanory, Bergman, Jafferis and Maldacena made important contribution on this problem. They constructed a three-dimensional N=6 Chern-Simons-matter theory and give strong evidence that this theory is just the low energy effect theory of mutli-membranes. In the last fifteen years, there have been many progresses in the study of this theory. In the talk, I will review some progress, focusing on BPS Wilson loops and integrable structure. Construction of various BPS Wilson loops will be reviewed. And features of integrable structure will be discussed. I will also show how Wilson loop can be used to make progress on an important problem about integrability of planar ABJM theory. Some unsolved problems including ones in general three-dimensional super-Chern-Simons theories will be discussed.

报告人：Jianbo Tang，University of New South Wales

时间：12月20日（周三）10:00

单位：中科院物理所

腾讯会议ID:  364-164-471

会议密码：1220 

摘要：

The renaissance of liquid metals has created unprecedented opportunities for broad disciplines intersecting materials science, engineering, advanced manufacturing, and nanotechnology. This is particularly true when it comes to the synthesis of strategically important metal fine structures that are backbones of numerous cutting-edge technologies. Recently, we have demonstrated that liquid metals can be used as special metallic synthesis solvents for renovating metal material design. In this seminar, I will talk about my research revolving around liquid metal-based crystal synthesis. I will touch on the unique metal-metal interactions and surface/interface critical phenomena that stimulate the structural development in liquid metal systems. The synthesis methods, distinguishing features, and potential applications of liquid metal-grown crystals will be discussed. This focused case study is meant to serve as one exemplar to showcase the great potential of liquid metals for driving material innovations and technological advancements.

报告人简介：

Dr. Jianbo Tang is a Lecturer (Assistant Professor) at the School of Chemical Engineering, Faculty of Engineering, University of New South Wales (UNSW Sydney), Australia. Currently, he is leading an independent group of 5 PhD students, 1 master by research student, and 2 postdoctoral research associates. He received his bachelor’s degree in 2011 from Xi’an Jiaotong University (Xi’an, China) and PhD degree in 2016 from the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences (Beijing, China). He was a postdoctoral fellow at Tsinghua University (Beijing, China) from 2016 to 2018 and at UNSW from 2018 to 2021. He has published >80 peer-reviewed articles, with first author and/or corresponding author papers in prestigious journals including Science, Nature Nanotechnology, Nature Synthesis, and Nature Communications. His publications have attracted >3,000 citations, and his current h-index is 32.

报告人：吕博，天津大学

时间： 12月20日（周三）14:00

单位：中科院物理所

地点 ： M楼253会议室

摘要：

三维强拓扑绝缘体具有Dirac锥结构的特殊表面态，在磁性、超导等材料的近邻效应作用下，可以打开能隙形成陈数相关的新二维拓扑系统。理论预测在拓扑绝缘体表面构造的异质结结构中，可以存在手征马约拉那费米子。这种粒子对输运性质的影响以及在拓扑量子计算等方面的应用一直以来是人们关注的领域。本报告分为两部分：1，介绍d波配对下拓扑绝缘体表面的约瑟夫森结中可以出现反常的电流-相位关系，同时试图从磁镜面反射对称的角度加以解释。该工作可能对强拓扑绝缘体上诱导出的超导对称性的分辨上带来应用。2，介绍拓扑绝缘体表面的约瑟夫森结中的二极管效应。试图阐述如何利用配对对称性，门电压调控，面内磁场等多种方法来获得约瑟夫森二极管，并使其具有可观的效率。手征马约拉那费米子的出现也对二极管效率产生重要影响。理论计算还发现该系统中二极管的极性可以出现反常的符号变化，与类似系统的实验有较好的符合。报告将利用多通道下的反常电流-相位依赖关系对上述现象加以解释。

报告人简介：

吕博，天津大学物理系特聘研究员。南开大学本科，2013年于北京大学获得博士学位，先后在名古屋大学、曼彻斯特大学从事博士后研究工作。2018年10月入职天津大学。主要研究方向为超导体系相关的输运现象与应用。

报告人：Zheng Liu，Tsinghua University

时间：12月20日（周三）15:00

单位：北京大学物理学院

地点 ： 物理楼，西563会议室

摘要：

In a condensed matter system, the hyperfine levels of nuclei reveal important information on the electronic properties，based on which novel experimental techniques are developed. In the computational physicscommunity, meanwhile, decades of efforts have also been made to reliably predict the key ingredients governing the hyperfine splitting in first principle, such as the hyperfine coupling constant and the electric field gradient at a nuclear site. This talk aims to show that by carefully designing the calculation, this computational power can be extended to exotic quantum materials, which further provides useful clues to understand novel experimental observations. The discussionwill mainly be based on frustrated or seemingly frustrated magnets, including Cu3Zn(OH)6Cl2.Cu3Zn(OH)6FBr, CaFeTi2O6 and 1T-TaS2.

报告人简介：

Zheng Liu is currently a member at Institute for Advanced Study, Tsinghua University. He works on thintersection of condensed matter physics and materials science, particularly focusing on briding thetheoretical frontier with first-principles calculation.

报告人：田传山，复旦大学

时间：12月20日（周三）15:10

单位：北京大学物理学院

地点 ： 物理楼中楼212

摘要：

Ultrashort energetic terahertz (THz) pulses have opened up exciting new avenues of research in the field of light-matter interactions. For material studies in small laboratories, researchers often require widely tunable femtosecond THz pulses with a peak field strength close to MV/cm. Currently, these pulses can be generated through optical rectification and difference frequency generation in crystals without inversion symmetry. We present in this talk a novel approach for generating THz pulses with no frequency tuning gap. Our method is based on Raman-resonance-enhanced four-wave mixing in centrosymmetric media, specifically diamond. We demonstrate that this technique enables the generation of highly stable, few-cycle pulses with near-Gaussian spatial and temporal profiles. Using a 0.5-mm-thick diamond, we were able to generate THz pulses with a stable and controllable carrier-envelope phase. These pulses carried approximately 15 nJ of energy per pulse at 10 THz, with a peak field strength of about 1 MV/cm at the focus. Experimental measurements of the THz pulse characteristics were in good agreement with theoretical predictions. Furthermore, we discuss additional advantages of our scheme, including the potential for improving the THz output energy to even higher levels.

报告人简介：

Chuanshan Tian received his B.S. and Ph.D from Fudan university in 2001 and 2006, respectively. From 2006 to 2010, he has been a postdoctoral researcher at Univ. of California at Berkeley. At the end of 2010, he joined the physics faculty at Fudan Univ.. His research interest includes the development of novel surface nonlinear optical spectroscopy and surface science.

报告人：苟健，浙江大学

时间： 12月21日（周四）10:00

单位：中科院物理所

地点 ： M楼253会议室

摘要：

Bismuth (Bi) is known for its unique electronic properties, owing to its distinctive position in the periodic table of elements. In this talk, I will discuss three types of two-dimensional (2D) Bi materials studied through molecular beam epitaxial (MBE) and low-temperature scanning probe microscopy (STM/qPlus-AFM). Firstly, we found, due to the large spin-orbital coupling (Soc) and close electronegativity between Bi and Sn, the introduction of Sn in Sn2Bi produce a giant Rashba splitting and asymmetric electron-hole band structure at the Fermi surface. Secondly, the anisotropic structure of black phosphorous-like Bi (BP-Bi) monolayer enables the creation of a single-layer honeycomb Bi (bismuthene) with various twist moiré superlattices, in which the modulation of topological edge states has been observed. finally, take the advantage of high resolution of qPlus-AFM measurement, we discovered that weak sp orbital hybridization of Bi facilitates electron transfer between sublattices and in-plane polarization switching in elementary BP-Bi monolayer. This observation confirms the emergence of novel single-element ferroelectric states in the realm of solid-state physics.

报告人简介：

苟健，研究员，博士生导师。2018年毕业于中国科学院物理研究所，获博士学位，随后进入新加坡国立大学物理系从事博士后研究工作。2023年加入浙江大学物理学院。研究领域有表面及低维物理、二维拓扑材料、二维铁电铁磁、超高真空低温扫描探针技术（STM/qPlus-AFM）、分子束外延生长（MBE）。已发表30余篇SCI文章，相关工作以第一/通讯作者发表在Nature、Physical Review Letters、Science Advances、Advanced Materials、National Science Review、ACS Nano等期刊。

报告人：史书园，北京航空航天大学

时间：12月21日（周四）14:00

单位：中科院物理所

腾讯会议：909-634-461

会议密码：1221

摘要：

基于自旋轨道矩（SOT）的新一代存储和逻辑器件利用电子的自旋自由度作为信息载体，具有数据非易失，低功耗及高速等优势，是后摩尔时代新器件发展的一个重要方向。受限于传统自旋材料的高对称性，SOT存储器件需借助外磁场来实现垂直磁矩的确定性翻转即信息的确定性写入，这显著增加了器件复杂性和成本。为实现无外场辅助的全电学SOT器件，具有结构对称性破缺的薄膜材料体系由于可诱导非传统SOT而受到广泛关注。我们分别基于镜面对称性破缺的第二类外尔半金属WTe2、亚晶格对称性破缺的线性反铁磁Mn-2Au、以及人工可控的成分梯度合金TaxTi1-x作为SOT层，实现了垂直磁矩的全电学确定性翻转，同时探讨了非传统SOT在磁矩翻转过程中的关键作用以及人工梯度合金在SOT调控方面的优势。最后我们设计了基于人工调控自由度更高的TaxTi1-x/CoFeB/MgO异质结的自旋逻辑器件。

报告人简介：

史书园，北京航空航天大学教授，北京市科技新星。本科毕业于哈尔滨工业大学英才学院电子信息科学与技术专业，博士毕业于新加坡国立大学，2019-2021年于新加坡国立大学从事博士后研究，先后在韩国科学技术院及美国橡树岭国家实验室交流访问。从事拓扑信息材料、自旋电子材料及其异质结相关的自旋电子学现象与器件研究。获2019年国际磁学与磁性材料大会（MMM）最佳口头报告奖(1名每年)，2020年新加坡微电子学会奖(1名每年)等。以第一作者（含共一）或通讯作者在Nature Nanotechnology, Nature Materials, Nature Communications, Advanced Materials, Advanced Functional Materials等期刊发表论文，申请美国/国内专利4项。

报告人：宋成，清华大学

时间： 12月21日（周四）15:00

单位：北京大学物理学院

地点：物理楼中212教室

摘要：

交错磁体（altermagnet）兼具铁磁自旋能带劈裂的特点和反铁磁无净磁矩且本征频率高的优势，是自旋电子学领域最新的研究热点之一。本报告将讲述课题组在典型的三种交错磁体（RuO2、Mn5Si3和CrSb）观察到的自旋输运现象。在RuO2中发现了交错磁自旋劈裂效应媒介的、取决于奈尔矢量方向的电荷-自旋转化过程及其逆过程。进而探索了电学翻转Mn5Si3的奈尔矢量方向，提出了基于不对称翻转能垒的奈尔矢量电学180度翻转新机制，并利用交错磁体中奈尔矢量产生的反常霍尔效应进行电学读出。通过设计特殊的磁对称性，可以在CrSb中观测到无辅助磁场的100%磁畴翻转。

报告人简介：

宋成，博士，清华大学长聘教授，国家杰出青年科学基金获得者。研究方向为信息功能材料，主要包括自旋电子学材料、声表面波滤波器和磁声耦合器件。在Nature Materials和Nature Electronics等期刊发表学术论文200余篇，论文被引用>1.2万次。曾获两项国家科技奖励、五项省部级科技奖励和首届“卓越青年研究生导师奖励基金”。兼任中国材料研究学会常务理事/青委会主任、中国真空学会理事/薄膜专委会副主任。

报告人：Yong Shi，南京大学

时间：12月21日（周四）15:30

单位： 北京大学物理学院

地点：KIAA-Auditorium

摘要：

Dwarf galaxy integral survey is a program to obtain 3-D spectra of a volume/flux-limited sample of local dwarfs within 11 Mpc, along with a complementary sample of some exceptional dwarfs such as ultra diffuse galaxies. In this talk, I would like to give some early results from this survey including dark matter distribution, intermediate-massive black holes and interstellar media in dwarfs.

报告人简介：

Yong Shi received his Ph.D in astronomy in 2008 from the Department of Astronomy at the University of Arizona. He spent about four years in California Institute of Technology as post-doc, and then joined the faculty of Nanjing University in 2013. His main research area is galaxy formation and evolution through observations.

报告 人：Professor Dmitry Budker，Johannes Gutenberg University Mainz & University of California, Berkeley

时间：12月22日（周五）10:00

单位：中科院物理所

链接： https://www.koushare.com/lives/room/467642

摘要：

In zero- to ultralow-field (ZULF) NMR, one does not need magnets in some or all of the three stages of an experiment: polarization, encoding, and detection. This unusual NMR modality has witnessed rapid development since the advent of compact and sensitive noninductive sensors, especially, atomic magnetometers that are now available commercially. We will discuss several recent ZULF NMR experiments carried out by our group and collaborators, demonstrating applications in areas as diverse as searches for beyond-the-standard-model particles and interactions, monitoring chemical reaction dynamics in highly inhomogeneous samples within metal catalytic reactors. and detection of breaking down of membranes of biological cells as a result of chemotherapy. ZULF NMR may be combined with hyperpolarization and radioactive detection overcoming the sensitivity limitations. Remarkably, a wide variety of hyperpolarization techniques (including dynamical nuclear polarization, photochemically and parahydrogen induced polarization) are being used in conjunction with ZULF NMR.

报告人简介：

Dmitry Budker studied physics at the Novosibirsk State University, graduating in 1985 with an Honors Diploma and obtained his PhD from the University of California at Berkeley in 1993, his thesis winning the 1994 Award of the American Physics Society for the best Thesis in Atomic, Molecular, and Optical Physics. He has been on the faculty of Department of Physics, University of California, Berkeley since 1995. From 2014, he is a University Professor at the Johannes Gutenberg University and a Matter-Antimatter Section Leader of the Helmholtz Institute in Mainz, Germany. He is a Fellow of the American Physical Society, a recipient of the 2021 Norman F. Ramsey Prize in Atomic, Molecular and Optical Physics and in Precision Tests of Fundamental Laws and Symmetries, and a co-recipient of the 2021 Erwin Schrodinger Award of the Helmholtz Association for his work in nuclear magnetic resonance. He is an author of over 300 research articles, including five books. Current research is focused on testing fundamental symmetries of nature in experiments that utilize the methods of atomic, molecular, and optical physics, including development of all-optical sensors based on atomic vapors and color centers in diamond, zero- and ultralow-field nuclear magnetic resonance (ZULF-NMR), searches for dark matter and dark energy constituents (GNOME, CASPEr), physics of sodium laser guide stars, and measurement of atomic parity violation and other symmetry tests in atoms,molecules and ions.