Non-saturating Quantum Magnetization in Weyl semimetal TaAs

The study of the Dirac and Weyl semimetal compounds has been one of the hottest topics in condensed matter physics, yet their topological band structure is highly sensitive to subtle changes of some crucial parameters such as spin-orbit coupling and chemical potentials. The energy scale can be as small as a few meV, so that an ordinary spectral technique like ARPES is unable to discern the band structure details. Their transport properties are in accordance to the Berry curvature on the Fermi surface which can also occur in a gapped semimetal with generic band structure.

Prof. Shuang Jia in ICQM, Peking University, Prof. Hai-Zhou Lu in South University of Science and Technology, Dr, Jinlei Zhang in High Magnetic Field Laboratory and the collaborators recently conducted a series of high-field magnetization experiments on architype Weyl semimetal TaAs family. They suggested a deterministic criterion of the magnetic response for massless topological electrons. Adopting the probes of magnetic torque and parallel magnetization in strong magnetic fields, they observed a quasi-linear field dependent effective transverse magnetization and a strongly enhanced parallel magnetization when the system is in the quantum limit. These non-saturating signals in strong fields are distinct from the saturating magnetic responses for massive carriers.

This work can be found in Nature Communications 10, 1028 (2019). The first author for this work is Dr. Cheng-Long Zhang in ICQM and Prof. C. M. Wang in in South University of Science and Technology. This work is supported by National Science Foundation of China (Grant No. U1832214, No.11774007), the National Key R&D Program of China (2018YFA0305601) and the strategic Priority Research Program of Chinese Academy of Sciences, Grant No. XDB28000000.

Magnetic responses of the non-relativistic and relativistic fermions

a, b, c, d: The energy bands of non-relativistic (parabolic-band) fermions; g, i, h, j: The energy bands of -relativistic fermions; e, f: Calculated parallel magnetization (M_||) and effective transverse magnetization (M_T) of non-relativistic fermions are saturated in strong magnetic field. k, l: Non-saturated M of relativistic fermions.