Nonlinear photoconductivities and quantum geometry of chiral multifold fermions

Shift photoconductivity in the Haldane model

“…Recently, the geometric interpretation of nonlinear optical responses has lead to a connection to the field of topology [18][19][20]. In the shift current, the geometry of the wave function comes into play through the Berry connection A nn , which describes the relation between bordering wave functions belonging to the manifold with band index n. As a consequence of the role of geometric aspects, the shift current is enhanced in materials like Weyl semimetals [21][22][23][24][25][26].…”