Posted in | News | Nanomaterials | Graphene

Anomalous Light-Like Behavior Now Realized in 3D Bulk Material

Electrons were observed to travel in a solid at an unusually high velocity, which remained the same independent of the electron energy. This anomalous light-like behavior is found in special two-dimensional materials, such as graphene, but is now realized in a three-dimensional bulk material. High-resolution angle-resolved electron spectroscopy, stimulated by synchrotron x-ray radiation, was used to substantiate the theoretically predicted exotic electron structure.

Artist’s conception highlighting key features of electron behavior in bulk sodium bismuth and cadmium arsenic. The interactions in the three-dimensional lattice lead to electrons that travel at a fixed velocity, independent of the electron’s energy state. Image courtesy of SLAC National Accelerator Laboratory

The Impact

A stable bulk material has been discovered that shows the same physics found in graphene, which illuminated the detailed interactions of electron’s orbital motion and its intrinsic magnetic orientation. The new material will be a test ground for theories on how electron interactions in solids shape exotic electron behavior, including the highest electron mobility in bulk materials.

Summary

Investigations of electronic behavior have expanded beyond familiar systems of metals, insulators, and semi-conductors into the realm of strongly interacting electrons, which exhibit exotic relationships between the allowed electron velocities and their energy states. A key feature for the new materials is behavior in which the electron velocity does not depend on its energy. Such a relationship is a hallmark of photons, the energetic particles that make up a beam of light. This property is found in the new class of materials exhibiting a strong interaction between the electron trajectory and the electron spin alignment (called “spin-orbit coupling”). Two-dimensional versions of such systems (for example, grapheme) have been recently explored, but the systems are hard to work with because of their ultra-thin film nature. This work establishes graphene-like electronic behavior in the bulk three-dimensional materials Na3Bi and Cd3As2 and explains their exceptionally high electronic mobility. The required advances in electron spectroscopy techniques, used to investigate the electronic structure, employed an energy tunable bright x-ray source and a high-resolution spectrometer.

Funding

Funded by DOE Office of Science, Basic Energy Sciences, including support for the Advanced Light Source. Researchers from foreign institutions were supported by the Engineering and Physical Sciences Research Council (UK), the National Science Foundation of China, the National Basic Research Program of China, the International Science and Technology Cooperation Program of China, the China Scholarship Council, and Defense Advanced Research Projects Agency (USA).

Publications

Z.K. Liu, B. Zhou, Y. Zhang, Z.J. Wang, H.M. Weng, D. Prabhakaran, S.K. Mo, Z.X. Shen, Z. Fang, X. Dai, Z. Hussain, Y.L. Chen, “Discovery of a three-dimensional topological Dirac semimetal, Na3Bi.” Science 343 (6173), 864–867 (2014). [DOI: 10.1126/science.1245085]

Z.K. Liu, J. Jiang, B. Zhou, Z.J. Wang, Y. Zhang, H.M. Weng, D. Prabhakaran, S.K. Mo, H. Peng, P. Dudin, T. Kim, M. Hoesch, Z. Fang, X. Dai, Z.X. Shen, D.L. Feng, Z. Hussain, Y.L. Chen, “A stable three-dimensional topological Dirac semimetal Cd3As2.” Nature Materials 13, 677–681 (2014). [DOI: 10.1038/nmat3990]

M. Neupane, S.Y. Xu, R. Sankar, N. Alidoust, G. Bian, C. Liu, I. Belopolski, T.R. Chang, H.T. Jeng, H. Lin, A. Bansil, F. Chou, M. Z. Hasan, “Observation of a three-dimensional topological Dirac semimetal phase in high-mobility Cd3As2.” Nature Communications 5, 3786 (2014). [DOI: 10.1038/ncomms4786]

Tell Us What You Think

Do you have a review, update or anything you would like to add to this news story?

Leave your feedback
Your comment type
Submit

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.