  We employed first-principles density functional theory calculations guided by
group-theoretical analysis and demonstrated the control of
insulator-metal-insulator transition, polarization and two sublattice
magnetization in (LaFeO$_3$)$_1$/(CaFeO$_3$)$_1$ superlattice via. multi
structural mode coupling i.e., 'multimode coupling'. We have discovered a polar
A-type charge disproportionation mode, Q$_{ACD}$ (analogous to the A-type
antiferromagnetic ordering), and found that it couples with the trilinear
coupling, $Q_{Tri}$ mode (common in $Pnma$ perovskite oxides and involves three
structural modes), and lowers the symmetry further. By tuning the strength of
the coupling between the participating modes, the polar metallic phase, polar
zero bandgap semiconducting, and polar insulating phases can be obtained. Here,
$Q_{Tri}$ switches the polarization direction, whereas, Q$_{ACD}$ can trigger
insulator-metal-insulator transition along with the polarization switching. The
mechanism is true for any transition metal superlattices constituted with
$Pnma$ building blocks and with partially filled $e_g$ or $t_{2g}$ electron(s)
at the transition metal sites.
