【Nature】 BIT makes progress in material structure by constructing the first "Heterodimensional Super Structure"!
On Aug 31, 2022, Professor Zhou Jiadong and Professor Yao Yugui, School of Physics, Beijing Institute of Technology, Professor Wu Xiaosong, Peking University, Professor Kazu Suenaga from Japan and Professor Zheng Liu from Nanyang Technological University published "Heterodimensional Superlattice with In-plane Anomalous Hall Effect" in Nature. They proposed and constructed a new heterodimensional structure substance for the first time and observed the in-plane anomalous Hall effect in the room temperature based on this substance. The successful construction of this structure broke through the traditional knowledge of substances and structures, and created a new direction for the research of new substances and novel physical properties.
Superlattice structures are generally formed by different parent materials arranged in a certain period to form a new substance different from the parent material. The substance of this new structure is expected to exhibit novel physical properties not possessed by the parent material, such as ferromagnetic, ferroelectric and superconducting, which have potential applications in the fields of electronics, optoelectronics and new information devices. Conventional superlattice structures are mainly formed by the same dimensional matter in a certain arrangement, such as 3D-3D, 2D-2D and 1D-1D structures. These conventional superlattice structures are mainly produced by using molecular beam epitaxy methods.
The discovery of two-dimensional (2D) materials has opened new possibilities for constructing new superlattice structures. Structure construction refers to the construction of different 2D materials and other structured materials by artificial construction or chemical vapor deposition methods to create intercalated layers or heterogeneous structures of different dimensions. However, since the superlattice structures were proposed and prepared in 1970, the realization of intrinsic superlattice structures composed of different dimensional materials has been particularly difficult. To address this challenge, Professor Zhou Jiadong et al. proposed and realized for the first time a new heterodimensional superlattice structure, where 2D VS2 and 1D VS crossed with each other to form a new 2D - 1D form of intrinsic heterodimensional superlattice structure. Based on the unique structure of this material, the superstructure exhibits a large in-plane anomalous Hall effect in the room temperature. This new discovery provides a whole new direction of constructing new substances and discovering new physical properties.
Figure 1: Preparation and optical and other characterization results of VS2-VS heterodimensional superstructure
Different from the preparation of traditional superlattice structures, the realization of this new heterodimensional superstructure is a milestone.
1) Breakthrough in preparation method: the traditional superstructure preparation mostly uses molecular beam epitaxy method; the preparation of the superstructure with 2D materials as the parent material is mostly constructed manually, which leads to the difficulty in controlling the cleanliness of the material interface, and the intrinsic properties of the material cannot be observed. The one-step VLS growth mechanism of the superstructure provides a direction for the construction of new substances.
2）Breakthrough in material cognition: the thickness of this structure can be adjusted from tens of nanometers to several nanometers since the 2D material and 1D lines periodically overlap each other to form a stable heterodimensional superstructure. It breaks through the traditional superstructure material which can only form a simple interlayer with the same dimensional material or different material, which promotes the development of the material field.
Figure 2: Atomic structure of the heterodimensional VS2-VS supercrystal
3) Breakthrough in novel physical properties: Due to the existence of 1D VS and the mutual coupling with 2D VS2, the 2D-1D heterodimensional superstructure shows a large in-plane anomalous Hall effect at room temperature, which is completely different from VS2, V5S8 and other substances. The coupling between substances of different dimensions is promoted, providing the possibility to realize novel physical properties such as room temperature ferromagnetic semiconductor properties and high temperature quantum anomalous Hall effect.
Figure 3: In-plane anomalous Hall effect of VS2-VS heterodimensional superstructure
Note: This work was supported by the Key Research and Development Program of the Ministry of Science and Technology, NSFC General Projects, the National Young Talent Program, the Key project of the National Natural Science Foundation of China, the Innovation Project of Beijing Institute of Technology, and the Provincial and ministerial Quantum Laboratory.
About the Author
Professor, School of Physics, Beijing Institute of Technology
He graduated from Nanyang Technological University (NTU), Singapore in 2017 with a Ph.D. and subsequently conducted research work at NTU, Singapore as a postdoctoral fellow. He joined the Beijing Institute of Technology in 2020 and was selected to the National Young Talent Program in the same year. He serves as an editorial board member of Chinese Chemical Letters and a young editorial board member of journals including Materials Horizons, Rare Metals, Smartmat, Nano Researchs. He is dedicated to the research of controllable preparation, novel physical properties and applications of novel two-dimensional quantum and semiconductor materials. He has published more than 100 papers so far, including Nature (2), Nat Mater, Nat Electron, Nat Commun, etc., with more than 6400 citations and h-factor 41. Since 2022, with Beijing Institute of Technology as the communication unit or the first unit, his research results have been published in Nat.Electronics, Nat.Mater., and Nature.
The outstanding achievements are attributed to the university's in-depth implementation of the strategy of "strengthening the university with talents". In recent years, the number of talents in BIT has been growing rapidly and innovative achievements have been emerging. What is the secret behind this?
Building a Global Talent Selection and Recruitment System
Since 2016, the university has held 8 consecutive sessions of International Young Scholars Forum, and organized overseas special sessions and activities of "Entering BIT". The university has set up 23 workstations for overseas talents, given full play to the effectiveness of the workstations, conducted more than 50 job fairs in famous international universities, and opened the door to international talents; established a big data analysis system, focused on attracting talent groups, contacted overseas young scholars, invited them to return back to China, and built the "China Dream" and "BIT Dream" together.
Establishing a "Special Talent Zone" Platform
The university innovates the mode of interdisciplinary, talent pooling, resource intensive guarantee and platform co-construction and sharing, and strives to build the incubator of emerging disciplines and reservoir of high-end talents. The university sets up new institutions including Advanced Research Institute of Multidisciplinary Science, Advanced Structure Technology Research Institute, School of Medical Technology, and build a number of high-level experimental platforms such as Analysis and Testing Center, Micro and Nano Processing Center, Quantum Physics Experiment Center, Advanced Materials Experiment Center, etc., which provides strong support for the scientific work of young talent and help them apply for major projects, win national awards, and publish high-level articles.
Building a Sound Talent Development System
The university provides precise support for the needs of talents at different stages. The innovation team plan, centering on the key technology bottlenecks, constructed a new talent introduction and education mechanism. So far, six innovation centers and 10 workshops for young scientists have been established. The "Teli Young Scholars" talent support program has been implemented to encourage outstanding young scholars to focus on the forefront of academic science and technology and carry out scientific research on the major strategic needs of the country. Since its implementation in 2018, 72% of "Teli Young Scholars" have been selected into the National Young Talent Program. Since 2016, more than 900 young teachers have been supported, providing a strong guarantee for the start of young teachers' scientific research. The "Teli Postdoctoral Fellows" program has offered opportunities for 81% of the postdoctoral fellows in Xuteli school to host national funds or projects during their stay at the station since its implementation in 2019.
Creating a Good Academic Atmosphere
The university has set up a regular academic exchange platform for young talents, promoting the communication of ideas and interdisciplinary integration, helping young talents to broaden their academic horizons and promote academic cooperation. BIT also holds "Academician Lecture Halls", "Hundred Lecture Halls", "Cross-Science Forum", "Frontier Crossing Forum", etc. Through the interactive mode of "report, question and discussion", BIT promotes young talent to have in-depth exchanges, mutual penetration and coordinated development with experts, to help young people find like-minded partners.
Rising the Quantity and Quality of the Talent Team
Since the "13th Five-Year Plan", the university has elected 6 new members of the two academies, and the number of outstanding young talents has increased by 10 times. BIT has assembled a high-level talent team led by more than 30 academicians, more than 130 leading academic talents and more than 220 outstanding young talents. The university has initially established a new system of "pre-appointment - long-appointment - full-time appointment" which is in line with international standards and has the characteristics of BIT, and has added more than 1,100 teachers with strong development potential to the new system. More than 1,100 new teachers with strong development potential have been added, and the size of the teaching staff has steadily increased, accounting for nearly 43% of the total full-time teachers in the current new system.
BIT regularly carry out employment evaluation exchange report
In total, more than 1000 postdocs have been recruited, and about 700 are currently in their stay, which is nearly six times that of the initial period of the "13th Five-Year Plan" construction. Among them, the proportion of doctoral graduates from overseas universities has increased from 5% to 13%. In 2021, postdoctoral fellows were approved for 235 projects of various kinds, among which 98 were approved for youth projects of National Natural Science Foundation of China, accounting for 56% of the total approved for similar funds in the university. The number of outbound teachers accounts for 44%. Post-docs have developed into a reserve force of young teachers and a force of scientific and technological innovation in the university.
In the future, the university will focus on building the "54321" pyramid of innovative talents, vigorously implement five major talent programs and five major improvement projects, and deepen five major reform tasks, so as to provide strong talent support for the construction of a world-class university with Chinese characteristics.
The development of the country depends on talents, and so does the revitalization of the nation. Beijing Institute of Technology will continue to implement the strategy of talent-rich university, support young people to take the lead, and continuously train and create outstanding talents to gather the surging power for the construction of a tech-driven nation!