University of Hong Kong
Recently, an intriguing magnetic-field driven crossover from positive to negative magnetoresistance (MR) has been observed in a variety of topological materials, where a notch-shaped longitudinal MR appears in the vicinity of the zero magnetic field and turns into a negative MR when the magnetic field exceeds some critical value. We first present a quantum interference theory for three dimensional Dirac materials. It reveals a striking crossover from positive to negative magnetoresistivity, uncovering strong competition between weak localization and weak antilocalization in multiple Cooperon channels at different chemical potentials. We then develop a quantum diffusive theory for massive Dirac materials in a finite uniform magnetic field. The quantum fluctuation of electromagnetic field still survives for massive Dirac fermion, and consequently, the quantum anomaly related longitudinal magnetoconductivity is found to be positive and quadratic in a magnetic field and decays quickly with the mass. Our work sheds light on the important role of spin-orbit coupling in the magneto-transport in in topological nontrivial and trivial Dirac materials.
 B. Fu, H. W. Wang, and S. Q. Shen, Phys. Rev. Lett. 122, 246601 (2019)
 B. Fu, H. W. Wang, and S. Q. Shen, Phys. Rev. B 101, 125203 (2020)
 B. Fu, H. W. Wang, and S. Q. Shen, Phys. Rev. Lett. 125, 256601 (2020)
Brief CV of Dr. Bo Fu:
Dr. Bo Fu received his Ph.D. in condensed matter physics in 2017 under the supervision of Prof. Qunxiang Li and Prof. Qinwei Shi at the University of Science and Technology of China. Currently, he worked in Prof. Shunqing Shen’ group at the University of Hong Kong as a postdoctoral fellow. His research mainly focuses on magneto-transport theory in Dirac materials and intriguing phenomena in higher order topological insulators and superconductors.
Contact: Shujuan Cui (崔書娟）
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