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The 384th forum: Magnetic Weyl semimetals: the Berry phase and more

Date: 2019-12-09
Time: 14:00
Venue: M234
Speaker: Associate Professor Binghai Yan(颜丙海)

Department of Condensed Matter Physics, Weizmann Institute of Science, Israel


Binghai Yan is an associate professor in the department of condensed matter physics at the Weizmann Institute of Science, Israel. After completing his PhD at Tsinghua University in 2008, he worked as a postdoc at Bremen University (Germany) and later at Stanford University (USA). He was a group leader in the Max Planck Institute for Chemical Physics of Solids (Dresden) during 2012-2016 and started his current position at Weizmann Institute since 2017. He was awarded the ARCHES Prize in Germany in 2013, and the Israel Physical Society Prize for Young Scientist in 2017. He is theoretical physicist and currently interested in solid-state materials that exhibit topological properties.


It is known that Bloch electrons pick up an anomalous velocity because of the Berry curvature in the magnetic material. The discovery of magnetic Weyl semimetals (WSMs) provides a novel, ideal platform to examine the Berry curvature-induced transport phenomena, such as the anomalous Hall effect (AHE) and the thermal version of AHE. First, we are interested in the anomalous Wideman-Franz law that governs the fundamental correlation between the charge and heat transport. We reveal a novel mechanism [1] to violate the Wideman-Franz law at the finite temperature by the Berry curvature distribution rather than the inelastic scattering effect, which is distinct from the ordinary (longitudinal) transport. Beyond the linear-response phenomena like AHE, WSMs can generate giant nonlinear optical response (such as the DC photocurrent), which is commonly attributed to the Berry curvature too. As a WSM turns magnetic, however, we find a new class of photocurrent by re-examining the nonlinear response theory [2,3]. It is contributed by the diabatic effect, instead of the Berry phase.

 [1] L. Xu et al. arXiv:1812.04339 (2018) [2] Y. Zhang et al. Nature Comm. 10, 3783 (2019). [3] T. Holder, et al. arXiv:1911.05667.

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