Nonlinear anomalous Hall effects probe topological phase-transitions in twisted double bilayer graphene

Abstract

Nonlinear anomalous Hall effect is the Berry curvature dipole induced second-order Hall voltage or temperature difference induced by a longitudinal electric field or temperature gradient. These are the prominent Hall responses in time-reversal symmetric systems. These band-geometry induced responses in recently realized twistronic platforms can probe their novel electronic band structure and topology. Here, we investigate the family (electrical, thermoelectric, and thermal) of second-order nonlinear anomalous Hall effects in the moiré system of twisted double bilayer graphene. We combine the semiclassical transport framework with the continuum model of twisted double bilayer graphene to demonstrate that the nonlinear anomalous Hall signals can probe topological phase transitions in moiré systems. We show that the whole family of nonlinear anomalous Hall responses undergo a sign reversal across a topological phase transition. Our study establishes a deeper connection between valley topology and nonlinear Hall effects in time-reversal symmetric systems.

Stacking Order Engineering of Two-Dimensional Materials and Device Applications

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Observation of room temperature anomalous Hall effect in graphene-WSe2 heterostructures

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“…Two-dimensional (2D) materials are gaining increasing attention due to their broad range of physical properties with practical applications in various fields. These include electronics [1][2][3][4] , energy storage 5 , transport 4,6,7 , optoelectronics [8][9][10] , sensors [11][12][13][14][15] , catalysis [16][17][18][19] and magnetism [20][21][22][23][24][25] . Among 2D materials 20,21,[25][26][27][28][29][30][31][32][33][34][35] , 2D magnets are highly desirable for use in modern spintronics and data storage devices.…”