Q & A with New CoE Faculty: Xi Dai

Monday, March 8, 2021
UC Santa Barbara’s College of Engineering has welcomed seven new faculty during the 2020-21 academic year, including Xi Dai, a new professor in the Materials Department. Before coming to UCSB, Dai, a leading expert in the theory of quantum materials, had been a Chair Professor in Physics at the Hong Kong University of Science and Technology (HKUST) and a Distinguished Professor at the Institute of Physics of the Chinese Academy of Sciences. He received his PhD in theoretical physics from the Institute of Theoretical Physics, Chinese Academy of Sciences and completed work as a post-doctoral researcher at Rutgers University, Boston University, and HKUST. 
Recently, we caught up with Dai to learn more about him. 
Q: What is the focus of your research?
The focus of my research is topological materials and correlated materials. 
Q: How did you get interested in these specific fields of research?
Correlation and topology are two main topics of modern condensed matter physics. The interplay between the two can generate an amazingly fruitful quantum world for us. Some of the phenomena we found in quantum materials are even beyond our imagination. This is such an active field with so much to uncover that you can never get bored with it. 
Q: What are the real-world implications of your research?
The research on quantum materials will lead to breakthroughs in the design and manufacture of new quantum devices, which can be used in the next generation of information technology.
Q: What do you see as the benefits of working in the UCSB Materials Department? 
Physicists like to work together to reveal the unbelievable quantum world. There are fantastic research groups in the university’s Materials Department working on the material design, synthesis and property measurement. I am really excited to join such a strong research team and can’t wait to work with the great scientists at UCSB! The university has a wonderful research environment, very active and energetic students and nice California weather. It is a dream place for me to continue my scientific career. 
Q: Please detail your recent research activities.
Most of my previous research activities have been concentrated in two fields. One is to develop computational methods for the electronic structure of the strongly correlated materials, while the second is to search for the topological non-trivial quantum state in realistic materials. 
In the first research field, I collaborated with Professor Z. Fang to develop the Gutzwiller density functional theory (LDA+Gutzwiller) and applied it to study many correlated materials, i.e. ferromagnetic metals, iron-based superconductors and topological Kondo insulators. In the second field, we have proposed several very important topological insulators, i.e. Bi2Se3, Bi2Te3 and Sb2Te3. We also proposed that a magnetic doped topological insulator thin film can realize a quantum anomalous Hall effect, which was confirmed by experiments in 2013. In 2015, we predicted the first Weyl semimetal material TaAs family, which was confirmed by both photo emission and transport experiments.
Q: What do the results of your research mean in terms of practical applications? Where might we eventually see the results in one or more applications that have an impact in our lives? 
My studies of correlated and topological materials reveal the deep connections among different degree of freedoms and among different forms of energy in the quantum materials. These exotic effects we found in quantum materials can transform both the information and energy from one form to another, providing countless opportunities for us to design new devices.
Q: What awards and honors have you received over the years ?
Over the past ten years I have received the Overseas Chinese Physics Association (OCPA) “Achievements in Asia Award” (2011), the Chinese Academy of Sciences (CAS) Prize for outstanding scientific achievements (2011), the KC Chou Foundation’s “Fundamental Physics Prize” (2014), the Zhou Pei Yuan Prize for Fundamental Physics by the Chinese Physical Society (2017), and the James C. McGroddy Prize for New Materials by the American Physical Society (APS) (2019).
Q: Tell us something interesting about yourself unrelated to work and research.
I am a basketball and soccer fan. Stephen Curry and the Golden State Warriors are my favorite player and team. I hope to get many opportunities to watch Curry play live because I live in California. I am also excited to watch the UCSB teams play. Biking is another hobby I developed quite recently. Goleta has some really beautiful biking trails, which I am eager to try out.

Xi Dai, professor of materials