Schematic structure of Te flakes and the performance of NLHE in Te devices. Credit: Prof. Zeng’s team
The team discovered a remarkable nonlinear Hall effect and radio rectification effect at room temperature in the elemental semiconductor tellurium (Te). The study is published in Nature Communications.
The Nonlinear Hall Effect (NLHE) is a second-order response to an applied alternating current (AC) that can generate a second harmonic signal without the introduction of an external magnetic field. The NLHE is of great scientific interest due to its potential applications in frequency doubling and rectification devices.
However, previous research has presented challenges such as low Hall voltage output and low operating temperature, which have hindered the practical application of NLHE. Currently, NLHE at room temperature has only been observed in the Dirac semimetal BaMnSb2 and the Weyl semimetal TaIrTe4, but both exhibit relatively small voltage output and lack tunability.
To address the challenge, the team decided to look for systems that exhibit good NLHE in semiconductor materials. They studied the nonlinear response of Te, a narrow bandgap semiconductor characterized by a one-dimensional atomic helical chain structure. This structure inherently breaks inversion symmetry, making Te an ideal candidate.
The research team discovered a remarkable NLHE in Te flakes at room temperature, where the Hall voltage output is tuned by an external gate voltage. At 300 K, the maximum second-harmonic output reaches 2.8 mV, an order of magnitude higher than the previous record. Further experimental and theoretical analysis showed that the NLHE observed in Te flakes is mainly caused by extrinsic scattering, and the breaking of the surface symmetry of the flake structure plays an important role.
Building on this breakthrough, the team replaced the alternating current with a radio frequency (RF) signal to achieve wireless RF rectification in the Te flakes. They achieved a stable rectified voltage output over a wide frequency range from 0.3 to 4.5 GHz.
Unlike conventional rectifiers that rely on p-n or metal-semiconductor junctions, Hall rectifiers based on the intrinsic properties of Te offer a broadband response under zero bias, making them an attractive option for developing efficient and reliable energy harvesting and wireless charging devices.
By revealing the underlying mechanism of NLHE in Te, this study not only deepens our understanding of nonlinear transport in solid-state materials but also opens up new possibilities for the development of advanced electronic devices in the future.
The team was led by Professor Zeng Changgan and Associate Researcher Li Lin of the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS).
Further information: Bin Cheng et al., “Giant nonlinear Hall effect and radio rectification at room temperature in elemental semiconductor tellurium,” Nature Communications (2024). DOI: 10.1038/s41467-024-49706-y
Provided by University of Science and Technology of China
Citation: Observation of a Tunable Nonlinear Hall Effect at Room Temperature in Tellurium (September 16, 2024) Retrieved September 16, 2024 from https://phys.org/news/2024-09-tunable-nonlinear-hall-effect-room.html
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