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    Home / Research / Academics / Content
    Nature Physics publishes Qiu Chunyin's latest findings on phononic crystals?
    Author:Zhang Yifei  Date:2019-03-19  Clicks:

    On March 4th, 2019, Nature Physics published online a paper by Professor Qiu Chunyin from the School of Physics and Technology, Wuhan University. The paper, entitled Phononic  Landau quantization and quantum-Hall-like edge states, reports his latest findings on phononic phononic  crystals.

    Funded by the Chinese Ministry of Science and Technology's 973 Program and the Chinese National Natural Science Foundation, the first named signatory on this paper hails from Wuhan University. Wen Xinhua, a master degree student in the School of Physics and Technology at Wuhan University, is the first author, Qiu Chunyin is the corresponding author, and Dr. Zhang Fan from the University of Texas at?Dallas also contributed to this research.

    Electrons are known to exhibit a large number of interesting transport effects under the action of strong magnetic fields. In a previous study published in 2010, A.K. Geim et al pointed out that applying an appropriate stress field to graphene can induce an effective gauge field and make electrons behave as they do in a real magnetic field. This work provided new inspiration for mechanical manipulation of quantum transport and exploration of strong field physics.

    Recently, Qiu Chunyin and his team have constructed a giant uniform pseudomagnetic field in phononic crystals. Utilizing the controllability of the phononic macroscopic platform, they directly observed the relativistic  phononic Landau quantization phenomenon and the zero-level sub-lattice polarization effect. They thus found that edge states phononic can be induced by phononic pseudomagnetic fields, something that had not previously been captured in graphene and other two-dimensional systems. These new findings not only constructs a complete framework for artificial uniform pseudomagnetic field systems, but also offer new methods for manipulating sound waves (note: unlike electrons, the response of sound waves to magnetic fields is almost negligible).

    (a) construction of the phononic  pseudomagnetic field, (b) phononic  Landau levels,(c) experimental detection of edge states

    Unlike the triaxial stretching mechanism of the graphene system generating the pseudomagnetic field, this simpler uniaxial deformation scheme avoids lattice distortion and facilitates the forming of uniform pseudomagnetic field in a large area. As shown in figure (a) of the report, the samples, triangular lattice phononic crystal composed of elliptical scatterers, can generate a uniform pseudomagnetic field if linear gradient-changing elliptical factors are introduced in the vertical direction. These phenomena were experimentally verified by 3D-printing actual samples, as shown in figures (b) and (c). All experimental results are consistent with theoretical predictions and numerical calculations.

    The significance of this research is the provision of a simple construction scheme of phononic  pseudomagnetic fields that can be equally applied to some other classical wave systems; the relativistic Landau quantization observed in this research brings a new mechanism for enhancing phononic radiation with its high density; The detection of the edge states induced by the uniform pseudomagnetic field fully unveils the characteristics and advantages of the phononic system.

    Recent years have witnessed significant achievements by Qiu Chunyin on topological properties of phononic crystals. He has co-authored many research papers in top journals, including Nature (2018), Nature Physics (2017; 2019), Phys. Rev. Lett (2016; 2018). In 2019, he was selected as part of the fourth batch of the national “Ten-Thousand Plan” Youth Top Talents project.

    Link to the paper: https://www.nature.com/articles/s41567-019-0446-3

    Rewritten by Wang Anqi

    Edited by Zhang Shiqi, Shen Yuxi, Hu Sijia & Shi Weiya


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