Table 2 Ferroicity-driven nonlinear photocurrent switching.

Second-order nonlinear photocurrent SC and CC responses are directly correlated with the intrinsic ferroic orders (±P, ±ϵ) of 2D MX materials and external linear (↔ , ↕) and circular ( ⟲ , ⟳) polarization of incoming light. A total of 16 types of in-plane nonlinear photocurrents can be generated by controlling four ferroic states and four types of light polarizations.

Nonlinear photocurrent
(Jx, Jy)
Ferroelectric order
+PP
+Px
if ϵxx > 0
+Py
if ϵyy > 0
Px
if ϵxx > 0
Py
if ϵyy > 0
Ferroelastic orderϵxx < 0 and ϵyy > 0(JCC,,JSC,)(JCC,,JSC,)
−ϵϵxx > 0 and ϵyy < 0(JSC,,JCC,)(JSC,,JCC,)