[institut] Center for Solid State Physics and New Materials seminar: Xiang Yuan Tuesday, August 13th 2024 13h

[yelena]

Dear colleagues,

You are kindly invited to the Center for Solid State Physics and New 
Materials seminar, which will be held on Tuesday, August 13th, 2024, at 
13:00, in the library reading room "Dr. Dragan Popović" of the Institute 
of Physics Belgrade.

The talk, entitled "Topology physics in new dimensions," will be given 
by Prof. Xiang Yuan from the East China Normal University, Shanghai, 
China

Abstract:
Generally, physical law varies with the dimensions of systems. In 
solid-state physics, quantized magnetic fields can effectively drive the 
electronic states into new dimensions, revealing the unique quantum 
phenomena. In this report, we will introduce our advances in topology 
physics within new dimensions including the discovery of 1D Weyl 
fermion, 3D Van Hov Singularity and 3D quantum Hall effect. The quantum 
Hall effect (QHE), discovered decades ago, remains one of the most vital 
phenomena in condensed matter physics. We extend the QHE from two 
dimension to three dimension and discover the bulk contribution from 
Weyl orbits by fabricating the wedge-shaped Cd3As2 nanostructures and 
conducting magneto-transport measurements[1]. To detect electronic 
states in a larger energy range under magnetic fields, we develop the 
optical pipe probe coupled with a closed-cycle superconducting magnet 
and the FTIR spectrometer, allowing experimental energy range from 
several meV to eV. Utilizing ultra-high magnetic fields (up to 35 T), 
the topological insulator HfTe5 is driven into the extreme quantum 
limit. With the one-dimensional Weyl mode realized, we detect the 
divergent optical conductivity of one-dimensional massless Weyl 
fermions[2]. Additionally, we control the exchange effect in topological 
magnet EuCd2As2 by external magnetic fields and realize a rare case of 
three-dimensional van Hove singularity evidenced by magneto-infrared 
spectroscopy[3].

References:
1.	C. Zhang#, Y. Zhang#, X. Yuan#, S. Lu, J. Zhang, A. Narayan, Y. Liu, 
H. Zhang, Z. Ni, R. Liu, E. S. Choi, A. Suslov, S. Sanvito, L. Pi, H.-Z. 
Lu, A. C. Potter & F. Xiu. Quantum Hall effect based on Weyl orbits in 
Cd3As2. Nature 565, 331–336 (2019).
2.	W. Wu, Z. Shi, Y. Du, Y. Wang, F. Qin, X. Meng, B. Liu, Y. Ma, Z. 
Yan, M. Ozerov, C. Zhang*, H.-Z. Lu, J. Chu & X. Yuan*. Topological 
Lifshitz transition and one-dimensional Weyl mode in HfTe5. Nat. Mater. 
22, 84–91 (2023).
3.	W. Wu, Z. Shi, M. Ozerov, Y. Du, Y. Wang, X.-S. Ni, X. Meng, X. 
Jiang, G. Wang, C. Hao, X. Wang, P. Zhang, C. Pan, H. Pan, Z. Sun, R. 
Yang, Y. Xu, Y. Hou, Z. Yan, C. Zhang, H.-Z. Lu, J. Chu & X. Yuan*. The 
discovery of three-dimensional Van Hove singularity. Nat Commun 15, 2313 
(2024).


Best Regards,
Jelena Pesic



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Institute of Physics Belgrade
Pregrevica 118, 11080 Belgrade, Serbia
http://www.ipb.ac.rs/