Background

Bismuth is a traditional semimetal, the rhombohedral structure of crystalline bismuth at ambient pressure is the outcome of lowering the cubic symmetry by pulling the cube along its body diagonal axis. The chemical potential drifts at high magnetic fields. Moreover, the twin boundaries further complexify the interpretation of the data by producing extra anomalies in the extreme quantum limit. Here, we present an extensive study of the Shubnikov-de Haas effect (Fig. 1a), Nernst effect, ultrasound, and magneto-optics in semimetal bismuth under a strong magnetic field.

What we discover?

All observed anomalies (Fig. 1b) can be explained in a single particle picture of a sample consisting of two twinned crystals tilted by 108°. Then, the mysterious ~ 40 T anomalies observed in S_xy, in second derivate of magnetosistivity, and in Δv as the field along the trigonal axis of the main crystal, can be explained by the intersection between the 0_e−Landau level of the twinned domain (Fig. 1c). The two adjacent crystals keeping their own chemical potentials despite a shift between chemical potentials as large as 68 meV at 65 T (Fig. 1d). This implies an energy barrier between adjacent twinned crystals reminiscent of a metal- semiconductor Schottky barrier or a p-n junction.

Why is this important?

How does the energy barrier form when the main and twin crystal crystals are semimetal? We argue that this barrier is built by accumulating charge carriers of opposite signs across a twin boundary. And this could be a new type of barrier, occurring between two semimetals. Similar to what Landauer proposed, there is an unshielded dipole field in the point like scattering center inside the metal. This new type of energy barrier between metals can be validated in future.

Why did we need WHMFC?

WHMFC provides an important measurement platform for this work. The magnetoresistance experiments are obtained in Wuhan National High Magnetic Field Center in China andNational High Magnetic Field Laboratory(NHMFL-PFF), Los Alamos National Laboratory in USA.The magneto-optics measurements are obtained in the Institute for Solid State Physics (ISSP), the University of Tokyo in Japan. The Nernst effect measurements up to 45 T are obtained in National High Magnetic Field Laboratory in USA. The ultrasound measurements are obtained in Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL) in France.

Who did the research?

Yuhao Ye¹, Akiyoshi Yamada^2,3, Yuto Kinoshita³, Jinhua Wang¹, Pan Nie¹, Liangcai Xu¹, Huakun Zuo¹, Masashi Tokunaga³,Neil Harrison⁴, Ross D. McDonald⁴, Alexey V. Suslov⁵, Arzhang Ardavan⁶, Moon-Sun Nam⁶, David LeBoeuf⁷, Cyril Proust⁷, Benoît Fauqué⁸, Yuki Fuseya², Zengwei Zhu¹and Kamran Behnia⁹

¹Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China

²Department of Engineering Science, University of Electro-Communications, Chofu, Tokyo 182-8585, Japan

³Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan

⁴MS-E536, NHMFL, Los Alamos National Laboratory, Los Alamos, NM 87545, USA

⁵National High Magnetic Field Laboratory, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310, USA

⁶Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, UK

⁷Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), CNRS, UGA, UPS, INSA, Grenoble/Toulouse, France

⁸JEIP, USR 3573 CNRS, Collège de France, PSL Research University, 11, place Marcelin Berthelot, 75231 Paris, Cedex 05, France

⁹Laboratoire Physique et Etude de Matériaux (CNRS-UPMC) ESPCI Paris, PSL Research University, 75005 Paris, France

Acknowledgments

This work was supported by The National Key Research and Development Program of China (Grants No.2022YFA1403500 and 2016YFA0401704), the National Science Foundation of China (Grant No. 12004123, No. 11574097 and No. 51861135104), and by directors funding grant number 20120772 at LANL. N.H. and RMcD acknowledge support from the US-DOE BES’Science of 100T’ program. B. F. acknowledges support from Jeunes Equipes de l’Institut de Physique du Collége de France (JEIP). K. B. was supported by the Agence Nationale de la Recherche (ANR-19-CE30-0014- 04). Y. F. was supported by JSPS KAKENHI grants 23H04862, 23H00268, and 18KK0132. Work performed at National High Magnetic Field Laboratory was supported by National Science Foundation Cooperative Agreements DMR-0654118 and DMR-2128556 and the State of Florida. M. T. acknowledges support from the JSPS KAKENHI grant No. 23H04862.

Link:https://www.nature.com/articles/s41535-024-00625-7