The Hefei Research Institute won the research on the three-dimensional Dirac semi-metal materials under the strong magnetic field.

Researcher Tian Liangming of the Strong Magnetic Field Science Center of the Hefei Research Institute of Materials Science, Chinese Academy of Sciences supported the water-cooled magnet and cryogenic test system of the steady-state strong magnetic field experimental device and made new progress in the research of the three-dimensional Dirac semimetal. Related research results online Published in the Physical Review B of the American Physical Society.

Three-dimensional topography Dirac semi-metal is currently the focus of research in the field of condensed matter and materials science. It has been hailed as a three-dimensional version of graphene. It is of great value in the application of low-energy electronic devices in the future, exploring the new Dirac. Semi-metallic materials are of great significance. Early studies showed that the layered material ZrTe5 is a thermoelectric material with excellent performance. Recent measurements of angle-resolved photoelectron spectroscopy and infrared spectroscopy have shown that the material may be a three-dimensional Dirac semi-metal material. However, there is no conclusive evidence of electrical transport at present.

In this work, the researchers found that when the applied magnetic field is parallel to the direction of the measured current, the sample exhibits a significant negative magnetoresistance effect, and the negative reluctance is quickly suppressed after changing the direction of the magnetic field. This type of negative reluctance, which is highly sensitive to the angle between the current and the magnetic field, is called the chiral magnetic effect and is also an important transport evidence for the experimental verification of the topological half-metal. In addition, by analyzing the behavior of quantum oscillations in ZrTe5, it was confirmed that the electrons in the sample have a high mobility and a very light effective mass while having a non-trivial Berry phase. The corner magnetoresistance measurements show that these Dirac electrons have distinct three-dimensional characteristics. At the same time, the researchers further measured the quantum oscillation behavior in the sample under a strong magnetic field (31T) and a very low temperature (300mK). It was found that these quantum oscillation peaks shatter as the temperature decreases because of the Langdao energy level splitting effect. This indicates that the Dirac point in the material may be split into two outliers due to the time-reversal symmetry breaking. These studies indicate that the layered ZrTe5 material is an ideal material system for the study of three-dimensional Dirac semimetals.

The research results were published in the American Journal of Physical Review [Phys. Rev. B 93, 115414 (2016)] with the title of Transport evidence for three-dimensional Dirac semimetal phase in ZrTe5. The research work was supported by the National Natural Science Foundation of China and Hefei University Science Center.

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