Abnormal nonlinear Hall effect in thin-film Weyl semimetals*

Type II Weyl semimetal possess exotic electronic properties arising from its unique topological structure near the Weyl nodes. Nonlinear Hall effect (NLH) is one of the most intriguing phenomenon is 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 filed 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 up to 2 orders below a critical temperature. We will also show angle-dependent and layer- dependent NLH measurements 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.