The University of Science and Technology of China made progress in the research of new topological materials Weir semiconductor

[ Instrument R & D of Instrumentation Network ] Recently, the user of the steady-state strong magnetic field experimental device (SHMFF) Professor Zeng Changgan of the University of Science and Technology of China discovered for the first time in a single-element semiconductor tellurium a chiral anomaly dominated by Waifermion and a magnetic field The number of periodic quantum oscillations successfully extends Weir physics to semiconductor systems. The research results were published online in the Proceedings of the National Academy of Sciences. The strong magnetic field experiment of this working part was completed on SHMFF water-cooled magnet.

Among the new quantum materials, topological materials with special energy band structures also possess novel electron transport characteristics. Related research can not only deepen the understanding of topological states, but also hope to promote the development of new high-performance electronic devices. A typical representative is the Weir semimetal system that has attracted widespread attention. Its transportation research often shows many characteristics such as large unsaturated magnetoresistance, negative magnetoresistance effect under a parallel magnetic field, and planar Hall effect. Arc also provides an electronic channel with high mobility and low power consumption. These characteristics are derived from the existence of the Fermion near Fermi. So far, researches on Weir fermions and Weir physics have been limited to semimetal systems. However, from the perspective of device applications, semiconductors have their unique value relative to semi-metals.

Tellurium is a narrow-band semiconductor. Due to the inversion of symmetry in space inversion and the corresponding strong spin-orbit coupling, there is a weir point where the band crosses near the top of the valence band. The team prepared a high-quality tellurium single crystal by physical vapor deposition, and its hole self-doping characteristics put the Fermi energy level at the top of the valence band, which significantly enhanced the impact of Waifermion on the transport properties.

The low-temperature transport study further revealed that tellurium single crystals exhibit typical magnetic transport characteristics due to chiral anomalies, including the negative magnetoresistance effect when the magnetic field is parallel to the current direction, and the planar Hall effect that occurs when the magnetic field is in the sample plane. On this basis, Professor Zeng Changgan's research group cooperated with Associate Researcher Xi Chuanying of the Strong Magnetic Center of Hefei Research Institute to test the electrical transmission performance under strong magnetic field with the help of WM1 belonging to SHMFF, and further discovered a rare magnetic field with a logarithmic magnetic field cycle Resistance and Hall resistance quantum oscillation.

This new type of quantum oscillation is a manifestation of self-similar discrete scale invariance, which can be attributed to the fine structure constant (7.5) in tellurium crystals is much larger than the value of vacuum (1/137), which makes the Waifermions and the opposite charge center Form a quasi-bound state in the form of a resonance state.

This work is the first to realize the "topological Weir semiconductor" which combines novel topological properties and semiconductor properties. If the Fermi energy level is adjusted from the valence band to the energy gap, a metal-insulator transition will occur, accompanied by a topological non-trivial state to a mediocre state. This unique characteristic of Weir semiconductors does not exist in Weir semimetals. The discovery of Waier Semiconductor provides new ideas for designing new topological semiconductor devices.

The research was supported by the National Natural Science Foundation of China, the Ministry of Science and Technology, the Chinese Academy of Sciences and Anhui Province.

Quantum oscillation behavior of magnetic resistance and Hall resistance measured under steady state strong magnetic field