In the realm of condensed matter physics, the exploration of the nonlinear Hall effect (NLHE) has emerged as a vibrant field of study. Recent advancements have been documented in a groundbreaking article published in Nature Communications, where a research team has unveiled the capabilities of tellurium (Te) regarding NLHE at room temperature. This semiconductor’s unique characteristics and its ability to generate second-harmonic signals without an external magnetic field are key breakthroughs that hold promise for technological innovations.
Historically, advancements in NLHE have been hampered by significant obstacles. Earlier studies have consistently reported low Hall voltage outputs and operational inefficiencies at elevated temperatures, which have stunted the development of practical applications. Notably, the phenomenon had only been recorded in a couple of materials such as BaMnSb2 and TaIrTe4, both of which exhibited modest voltage outputs and minimal tunability. Hence, the search for room temperature NLHE in new materials has been imperative for the advancement of devices that utilize this effect.
Recognizing the need for more effective materials, the research team turned their attention to tellurium, a narrow-bandgap semiconductor that features a helical chain structure. This unique atomic arrangement inherently breaks inversion symmetry, making Te an attractive subject for the examination of NLHE. Their experiments utilizing thin flakes of tellurium yielded promising results, exhibiting a tunable Hall voltage that can be adjusted through external gate voltages. Impressively, they recorded a maximum second-harmonic output of 2.8 mV at room temperature, which significantly surpasses previous achievements in the field by an order of magnitude.
Through a combination of theoretical analysis and experimental validation, the researchers uncovered that the substantial NLHE observed in tellurium thin flakes is heavily influenced by extrinsic scattering mechanisms. Notably, the surface symmetry breaking due to the thin flake structure plays a pivotal role in driving the NLHE response. This understanding contributes to a more nuanced grasp of nonlinear transport phenomena in solid materials, paving the way for enhanced applications.
The findings did not stop with NLHE. The research team also made strides in wireless rectification technology by substituting alternating current (AC) with radiofrequency (RF) signals. Their experiments revealed that Te thin flakes could achieve stable voltage outputs across a diverse frequency spectrum of 0.3 to 4.5 GHz. This innovative approach to rectification contrasts sharply with traditional methods that often depend on junctions. The inherent properties of tellurium facilitate a broadband response without the necessity of bias, positioning it as a viable candidate for future energy harvesting and wireless charging technologies.
The insights gained from this research not only enhance our understanding of nonlinear transport phenomena but also open new avenues for the development of advanced electronic devices. As researchers like Prof. Zeng Changgan and Associate Researcher Li Lin continue to unravel the potentials of tellurium, the implications for energy-efficient and reliable technologies are boundless. This significant breakthrough could lead to more practical, functional applications in various electronics, thereby revolutionizing the field and the technologies we rely on daily.