Abnormal Nonlinear Hall Effect in Few-Layer Weyl Semimetals

Type II Weyl semimetal possesses exotic electronic properties arising from its unique topological structure near the Weyl nodes. The nonlinear Hall effect (NLH) is one of the most intriguing phenomena in these materials which originated from the crystal inversion symmetry breaking. In NLH, the transverse Hall-like double-frequency voltage can be generated without the presence of any magnetic field and this unique electronic property is determined by quantum geometry, which is known as Berry curvature. In this presentation, we will show an abnormal nonlinear Hall behavior in a layered Type II Weyl semimetal TaIrTe₄. From the temperature-dependent NLH measurement, we find that the nonlinear response is greatly enhanced above 2 orders below a critical temperature. We will also show angle-dependent NLH measurements and second harmonic generation (SHG) results to reveal the mechanism of enhancing the NLH effect and how it is related to quantum geometry. A theoretical model is also established to explain the abnormal NLH effect.