Designing controllable cross coupling between polarization, magnetization, insulator-metal transition in oxide superlattices by multimode coupling*

We have employed first-principles density functional theory (DFT) calculations guided by group-theoretical analysis and demonstrated the polarization control of insulator-metal transition (IMT) in (LaFeO₃)₁/(CaFeO₃)₁ superlattice (LFO/CFO 1/1 SL). We have discovered a new charge disproportionation mode (ACD) in LFO/CFO 1/1 SL which is analogous to the A-type antiferromagnetic ordering. We found that the ACD mode couples with the tri-linear coupling (common in Pnma), Q_Tri ~ Q_RQ_TQ_AFEA where Q_R, Q_T, and Q_AFE represent rotation, tilt, and anti-ferroelectric A-site modes respectively. The observed multimode coupling, i.e.; Q_M ~ Q_Tri Q_ACD shows a large magnetization difference associated with the ACD mode. This particular mode coupling offers polarization control of metal-to-insulator transition and magnetization. Finally, we have discussed how structural, magnetic, and electronic properties are interlinked in LFO/CFO 1/1 SL leading to the design of multifunctional materials and can be tunable via strain.