Investigation of Berry curvature dipole in transition metal dichalcogenides

Conventional Hall effect requires a broken time-reversal (TR) symmetry for the generation of a transverse voltage in response to an applied electric field. Recently, Sodeman and Fu (2015) proposed another addition to the Hall effect family, a non-linear Hall (NLH) response, present in systems that preserve TR symmetry. This NLH current results from Berry curvature dipole (BCD) generated in non-centrosymmetric materials due to the asymmetric distribution of Berry curvature in the momentum space. From the initial prediction by Sodemann and Fu, breaking inversion is the key requirement to finite BCD, along with the constraint that the material has low crystal symmetries. In 2D materials, the maximum allowed symmetry for non-zero BCD is a single mirror plane. The distorted octahedral phase of transition metal dichalcogenides (TMDCs) is non-centrosymmetric with reduced symmetries, making them an excellent platform to observe and engineer NLH effect. Using first-principles DFT calculations and tight binding models, we have successfully identified monolayer and bilayer TMDCs that display finite BCD and hence, NLH currents^1,2. The identification and study of materials that display BCD can lead to a better understanding of its underlying quantum nature, all the while being promising platforms to observe and engineer non-linear Hall effects and their expected applications.



¹ Joseph et.al., Materials Research Express 8:124001 (2021).

² Joseph et.al., Journal of Physics: Condensed Matter 33:465001 (2021).