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Home People Research Research Publications Teaching Protocol Sharing News Center for Pain Medicine Research Brief Info Software Alumni Join us Contact us Chang Liu Google Scholar ResearcherID Associate Professor Department of Physics LIU Chang, Associate Professor at the Department of Physics, SUSTech. Dr. Liu's research mainly focuses on revealing the novel electronic properties of functional materials such as magnetic, topological, and thermoelectric materials, using angle resolved photoemission spectroscopy (ARPES) and other spectroscopic techniques. His research group also masters the techniques of material growth such as the flux method, chemical vapor transfer (CVT) and molecular beam epitaxy (MBE). On the field of magnetic materials, his work uncovers the spin splitting of energy bands in an unconventional antiferromagnet. In the field of topological materials, his works presented e.g., a gapless topological surface state in magnetic topological insulators and the Fermi arcs in three dimensional Dirac semimetals. Personal Profile Brief Introduction LIU, Chang, Associate Professor at the Department of Physics, SUSTech. Dr. Liu's research mainly focuses on revealing the novel electronic properties of functional materials such as magnetic, topological, and thermoelectric materials, using angle resolved photoemission spectroscopy (ARPES) and other spectroscopic techniques. His research group also masters the techniques of material growth such as the flux method, chemical vapor transfer (CVT) and molecular beam epitaxy (MBE). On the field of magnetic materials, his work uncovers the spin splitting of energy bands in an unconventional antiferromagnet. In the field of topological materials, his works presented e.g., a gapless topological surface state in magnetic topological insulators and the Fermi arcs in three dimensional Dirac semimetals.   Professional Experiences 2015-Present: Associate Professor, Department of Physics, SUSTech 2014-2015: Assistant Professor, Department of Physics, SUSTech 2011-2014: Postdoctoral Research Associate, Princeton University (USA)   Educational Background 2006-2011: PhD in Condensed Matter Physics, Iowa State University (USA) 2003-2006: BS in Department of Physics, Sun Yat-sen University (China) 2001-2003: Department of Urban Planning, Sun Yat-sen University (China)   Honors & Awards 2014: Recipient of the “Peacock plan Award”, Shenzhen   Selected Recent Publications 1. Yu-Peng Zhu*, Xiaobing Chen* et al., Observation of plaid-like spin splitting in a noncoplanar antiferromagnet. Nature 626, 523 (2024). 2. Xiang-Rui Liu*, Hanbin Deng*, Yuntian Liu* et al., Spectroscopic signature of obstructed surface states in SrIn2P2. Nat. Commun. 14, 2905 (2023). 3. Yu-Jie Hao*, Ming-Yuan Zhu*, Xiao-Ming Ma* et al., Single crystal synthesis and low-lying electronic structure of V3S4. J Alloys Compd. 949, 169776 (2023). 4. Xiao-Ming Ma*, Yufei Zhao*, Ke Zhang*, Shiv Kumar* et al., Realization of a tunable surface Dirac gap in Sb-doped MnBi2Te4. Phys. Rev. B 103, L121112 (2021) (Editors' Suggestion). 5. Ruie Lu*, Hongyi Sun*, Shiv Kumar*, Yuan Wang* et al., Half-magnetic topological insulator with magnetization-induced Dirac gap at a selected surface. Phys. Rev. X 11, 011039 (2021). 6. Xuefeng Wu*, Jiayu Li*, Xiao-Ming Ma*, Yu Zhang* et al., Distinct topological surface states on the two terminations of MnBi4Te7. Phys. Rev. X 10, 031013 (2020). 7. Chang Liu, Xiang-Rui Liu, Angle resolved photoemission spectroscopy studies on three dimensional strong topological insulators and magnetic topological insulators. Acta Phys. Sin. 68, 227901 (2019) (Invited Review). 8. Yu-Jie Hao*, Pengfei Liu*, Yue Feng* et al., Gapless surface Dirac cone in antiferromagnetic topological insulator MnBi2Te4. Phys. Rev. X 9, 041038 (2019) (Featured in Physics). 9. Wenke He et al., High thermoelectric performance in low-cost SnS0.91Se0.09 crystals. Science 365, 1418 (2019). 10. Xiao-Bo Wang*, Xiao-Ming Ma* et al., Topological surface electronic states in candidate nodal-line semimetal CaAgAs. Phys. Rev. B 96, 161112(R) (2017). 11. Qiangsheng Lu et al., Unexpected large hole effective masses in SnSe revealed by angle-resolved photoemission spectroscopy. Phys. Rev. Lett. 119, 116401 (2017). 12. Chang Liu et al., Tunable spin helical Dirac quasiparticles on the surface of three-dimensional HgTe. Phys. Rev. B 92, 115436 (2015). 13. Su-Yang Xu*, Chang Liu* et al., Observation of Fermi arc surface states in a topological metal. Science 347, 294 (2015). 14. Yang Xu, Ireneusz Miotkowski, Chang Liu et al., Observation of topological surface state quantum Hall effect in an intrinsic three-dimensional topological insulator. Nat. Phys. 10, 956 (2014). 15. Chang Liu et al., Spin-correlated electronic state on the surface of a spin-orbit Mott system. Phys. Rev. B 90, 045127 (2014). * First author with equal contribution Personal Profile Research Angle resolved photoemission spectroscopy (ARPES), Ultrahigh vacuum technique; Growth of single crystals and single crystalline films; Novel magnetic materials; Magnetic and nonmagnetic topological materials; High-performance thermoelectric materials; Two-dimensional materials. Teaching Teaching: “University General Physics Course B” (two semesters), “Principles and Applications of Physics Experiment Instruments”.  Awarded: Second Prize, 2017 Young Teacher Teaching Competition, Southern University of Science and Technology; 2018 Excellent Teaching Award, Southern University of Science and Technology. Publications Read More In recent years, the group’s representative scientific research achievements include: 1. Spectroscopic discovery of unconventional antiferromagnets Manipulating the spin of electrons in space, momentum and energy is the basis and core of spintronics. Traditional spintronics devices utilize ferromagnets as generators and manipulators of spin currents. However, the information storage density of ferromagnetic materials is not high, and the read/write speed is relatively slow (GHz level). In contrast, the information storage density of antiferromagnetic materials can reach the atomic level, and its unique terahertz (THz) spin dynamics enables magnetic moment reversal on the picosecond time scale. Therefore, the ideal next-generation spintronics material needs to have the characteristics of ferromagnets that are easy to write and read information, and also needs to have the ability of antiferromagnets to store information with high stability, high density and ultra-fast spin dynamic properties. Recently, attention has been paid to a previously overlooked set of symmetry operations in magnetic materials in the limit of zero spin-orbit coupling. These operations lead to the emergence of a new type of antiferromagnetically induced spin splitting, enabling the energy bands of antiferromagnets to achieve large, momentum-dependent spin polarization. The magnetoelectric properties of this unconventional antiferromagnet are even more similar to those of ferromagnets, so they have the advantages of both ferromagnets and antiferromagnets, and are expected to replace ferromagnets as the material basis for spintronics. In 2024, our group collaborated with Prof. Qihang Liu’s group in the Department of Physics, SUSTech, and Prof. Shan Qiao’s group at the Shanghai Institute of Microsystems and Information Technology, Chinese Academy of Sciences, to discover the first unconventional antiferromagnet using spin- and angle resolved photoemission spectroscopy and first-principles calculations. In the noncoplanar antiferromagnetic manganese ditelluride (MnTe2), we find that the in-plane component of the spin is antisymmetric with respect to the high symmetry planes of the Brillouin zone. This results in a special “plaid-like spin texture” in the antiferromagnetic ground state. This unconventional spin polarization signal almost disappears in the high-temperature paramagnetic state, suggesting that it originates from the intrinsic antiferromagnetic order. Our study demonstrates a new type of quadratic spin texture induced by time reversal breaking, laying a solid foundation for antiferromagnetic spintronics and paving the way for the study of exotic quantum phenomena in related materials. Our results were published in Nature on February 14, 2024. The same issue of Nature published a “News and Views” article titled “New type of magnetism splits from convention”, stating that our work “contribute key advances to the understanding of spin splitting in altermagnetic compounds — it shed light on the complexities inherent in the magnetic structures of these materials. The authors’ work will no doubt serve as a catalyst for accelerating research on this topic”. This work has been reported by the “headline news” and the international edition of the newspaper “Science and Technology Daily”, and public accounts such as “Observer Network” and “DeepTech”, and was selected as a cover story by China’s “Physics” magazine. 2. Discovery of gapless topological surface states in the magnetic topological insulator MnBi2Te4 The discovery of topologically-nontrivial phenomena is one of the most important developments in the field of condensed matter physics in the past 20 years, and magnetic topological materials are the latest research hotspot and breakthrough in this field. In 2013, Prof. Qi-Kun Xue’s research group at Tsinghua University used ferromagnetic-doped three-dimensional topological insulators to achieve the quantum anomalous Hall effect (QAHE) at extremely low temperatures, marking another milestone breakthrough in condensed matter physics. In 2017, researchers discovered stoichiometric ferromagnetic/antiferromagnetic TI phase in compounds represented by MnBi2Te4, which increased the realization temperature of external field-induced quantized Hall conductance by an order of magnitude, providing a way to achieve QAHE, “axion insulators”, high Chern-number Chern insulators, and other novel quantum phases at higher temperatures. Theoretically, these compounds have an A-type antiferromagnetic structure, and their topological surface states support a large magnetic energy gap on their natural cleavage planes. The existence of this energy gap is a necessary condition to realize axion insulators and topological magnetoelectric effects. In 2019, our group collaborated with Prof. Qihang Liu’s group in the Department of Physics, Prof. Chaoyu Chen’s group in the Institute for Quantum Sciences and Technologies, SUSTech, and the Hiroshima Synchrotron Radiation Lightsource Laboratory in Japan to address this issue. Using laser ARPES and systematic ARPES based on synchrotron light, we pointed out that the energy gap in the topological surface state of MnBi2Te4 is nearly zero. This discovery rewrites previous conclusions and brings the study of magnetic topological systems to a new stage. Our results were published in Physical Review X on November 21, 2019, and was featured in the Physics magazine from the American Physical Society. 3. Measurement of the valence band of thermoelectric material SnSe and discussion of its thermoelectric mechanism Thermoelectric materials are new energy materials that can directly convert thermal energy and electrical energy into each other. They have broad application prospects in thermoelectric refrigeration and waste heat power generation. They play an important role in improving the utilization rate of energy, providing a hope to alleviate the energy crisis. The tin selenide (SnSe) single crystal, discovered in 2014, has rewritten the history of single crystals not being able to become excellent thermoelectric materials. In 2017, our group collaborated with Prof. Jiaqing He’s group in the Department of Physics and Prof. Lidong Zhao’s group in Beihang University to use the ARPES instrument at the SUSTech Core Labs to measure the energy bands of undoped and hole-doped SnSe single crystals at different temperatures (80 – 600 K). The band structure has been systematically measured, providing an idea for quantitatively explaining the electrical properties in this temperature range. Our results were published in Physical Review Letters in 2017. Qiangsheng Lu, an undergraduate student in our group, is the first author of the paper. News More Group members report spectroscopic discovery of unconventional antiferromagnets 2024-02-27 Group member recognised as Top 10 Undergraduate Graduates at SUSTech 2023-06-17 Group members gain new insights in obstructed atomic insulators 2023-06-12 People Read More PrevNext UpDown Join us Read More Contact Us Contact Address Room P4113, College of Science, No. 1088, Xueyuan Rd., Nanshan District, Shenzhen, Guangdong 518055, China Office Phone 0755-88018221 Email liuc@sustech.edu.cn