Recent advancements in the field of material science have unveiled promising opportunities in the realm of nonlinear optics and electronics. A pivotal study published in Nature Communications has spotlighted the nonlinear Hall effect (NLHE) in tellurium (Te), an elemental semiconductor, at room temperature. Previous research on NLHE has primarily grappled with limitations such as subpar hall voltage outputs and low operational temperatures, which have restricted their applicability in practical scenarios. The discovery of significant NLHE in Te challenges conventional boundaries and expands the horizons for potential applications.
Historically, the study of NLHE has been confined to materials like Dirac semimetal BaMnSb2 and Weyl semimetal TaIrTe4. While these materials demonstrated NLHE, they also presented issues including limited voltage outputs and a lack of tunable properties. This spurred a search for alternative materials that could exhibit enhanced properties in a more versatile manner. The pursuit of semiconductor materials that display remarkable NLHE characteristics has been propelled by the necessity to overcome these technical obstacles and to leverage NLHE for industrial applications in areas such as rectification and frequency-doubling technologies.
The research team turned their attention to tellurium due to its distinctive one-dimensional helical chain structure, which disrupts inversion symmetry. This inherent characteristic positions Te as a promising candidate for achieving exceptional NLHE performance. The team’s investigation revealed that thin flakes of tellurium produced a significant Hall voltage output at standard room temperature, augmenting earlier findings by orders of magnitude. At a temperature of 300 K, the second-harmonic output hit an impressive 2.8 mV, representing a breakthrough in this field.
Understanding the mechanisms propelling NLHE in tellurium has been a focal point of the research. The team concluded that the dominant factor driving the notable NLHE observed is extrinsic scattering, significantly influenced by the unique surface symmetry breaking inherent in the thin flake structure. This critical insight highlights how structural properties can dictate the performance of electronic materials, further encouraging exploration in nanoscale materials engineering.
Going beyond the implications of NLHE, the research team made a leap by substituting AC current with radiofrequency (RF) signals, demonstrating a wireless RF rectification mechanism using tellurium thin flakes. This innovation yielded a stable rectified voltage over a broad frequency spectrum from 0.3 to 4.5 GHz, suggesting that Te-based Hall rectifiers can redefine the landscape of energy harvesting and wireless charging devices. This method distinctly contrasts with traditional rectifiers that depend on p-n junctions, thus offering a pathway to more efficient and adaptable energy solutions.
The findings from the University of Science and Technology of China (USTC), under the guidance of Prof. Zeng Changgan and Associate Researcher Li Lin, set a new paradigm for nonlinear transport in solid-state materials. Not only do these insights into the NLHE of tellurium enrich our fundamental understanding of semiconductor physics, but they also serve as a springboard for the advancement of innovative electronic devices that could significantly impact future technologies.
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