Main research field

Our team is devoted to investigating the mechanism of high-temperature superconductivity and relevant key scientific issues in practical applications based on the special techniques of superconducting single-crystalline film and high-throughput film.
Keywords: high-temperature superconductivity, single-crystalline film, materials genome.

1.High-throughput superconductivity research: preparation of epitaxial combinatorial film and interface via advanced high-throughput synthesis techniques, collaborated with the Center for Materials Genomes. The high-throughput synthesis and fast screening techniques are expected to accelerate the R&D of new (superconducting) materials.

2.Unveiling the mechism of high-temperature superconductivity: preparing high-quality single-crystalline films for some crucial system of oxide superconductors; focusing on the quantum critical effects induced by chemical doping, high magnetic field, electrostatic field; constructing the high-dimensional holographic phase diagram for high-temperature superconductors via combinatorial film.

3.Accelerate the practical use of superconducting films, collaborated with “practical superconducting thin film research” group at Songshan Lake Materials Laboratory. Focusing on the preparation of large-sized films, characterization of magnetism, and high-frequency response.

Recent highlights:

1.To accelerate the research on the mechanism, from quantitative differences to qualitative ones, we have developed the new generation of epitaxial composition-spread film techniques, as well as suitable fast-speed screening techniques, highly praised by international experts (e.g., “tour de force”). On the basis of the “tour de force” techniques, a scaling law has been unveiled between the high-temperature superconducting state and its “strange-metal” normal state (i.e., linear resistivity as a function of temperature). That is, the superconducting transition temperature scale with the square root of the slope of linear-in-temperature resistivity. Such a scaling law is also found to work for other unconventional superconductors, thereby points to a shared common mechanism between the strange-metal scattering and the unconventional electron pairing. This work was recently published in Nature (Nature 602, 431, 2022), evaluated as “one of the most excellent prototypes of materials genome initiative” and a “breakthrough” in the high-temperature superconductivity research.(APS March Meeting 2022 Focus Session)

2.To overcome the technical bottlenecks in the practical applications of high-temperature superconducting films, we have conceived and conducted a technical roadmap to develop domestic advanced equipment. Our group has successfully developed a combinatorial laser molecular beam epitaxy system integrated with specialized low-temperature scanning tunneling microscopy. In two years, we succeeded in developing a homemade multi-beam pulsed laser deposition system, in which high quality double-side 2 inch practical superconducting films have been successfully prepared (e.g. YBCO film with surface resistance below 0.1mΩ @77K,10GHz, and critical current density beyond 4MA/cm²@77K). Such a domestic system has exhibited the ability for depositing various large-size quantum materials, certified as “reached the international advanced level” by the certifying commission.

Other representative progresses:

1.Accelerating the research on the mechanism by virtue of single-crystalline films: a) depicting the phase diagram of the overdoped region of electron-doped cuprate for the first time, which has been adopted by Scalapino in the review published in Rev. Mod. Phys. 2012; b) discovering that the superconducting transition temperature is closely correlated to the scattering rate of strange metal state in electron-doped cuprate; c) unveiling the second quantum fluctuation related to superconducting boundary in electron-doped cuprate. These results have been published in Nature (2011) and PNAS (2012). On these basis, we have further constructed of the high-dimensional holographic phase diagram of electron-doped cuprate via magnetic field and ionic liquid gating, discovery two different insulator-superconductor transitions (Sci. Bull 2020) and quantum phase transition induced by magnetic field (PRB 2021).

2.Exploring novel superconducting family by thin film deposition: depicting the electronic phase diagram of spinel oxide LiTi₂O₄ for the first time via preparing superconducting, which also suggests the presence of an orbital-related state (Nat. Commun. 2015); studying the electron-phonon interaction, superconductor-insulator transition, and evolution of upper critical field (PRB 2019); achieving superconductivity in an orbital ordering insulator MgTi₂O₄ via structural engineering (PRB 2020), which is the second superconductor in the hundreds of spinel oxides; discovering two superconductor-insulator transitions in LiTi₂O₄ induced by ionic liquid gating, which unveils the similarity between heavy electron-doped LiTi₂O₄ and insulating MgTi₂O₄ (PRB 2021).

3.The innovation of high-throughput superconductivity research, via the developments of full set of advanced high-throughput experiment facilities to speed up the processes in searching for new superconductor, establishing experimental database and extracting new rules, based on which the first review article on this interdisciplinary branch was published in Supercond. Sci. Technol.

Funding Support

Our work was supported by the National Key Basic Research Program of China (2021YFA0718700 and 2022YFA1603903), the National Natural Science Foundation of China (11927808， 11834016，118115301, 11961141008, 12274439 and U23A6015), the Strategic Priority Research Program (B) of Chinese Academy of Sciences (XDB25000000), Beijing Natural Science Foundation (Z190008), Key-Area Research and Development Program of Guangdong Province(2020B0101340002), Basic Research Youth Team of Chinese Academy of Sciences (2022YSBR-048).