Polar and electronic phase control through interacting structural modes

Le résumé fourni par la source

Abstract We demonstrate the control of coupled structural, electronic, and magnetic degrees of freedom in oxide superlattices using ( LaFeO 3 ) 1 / ( CaFeO 3 ) 1 as a concrete model system. Combining symmetry-mode analysis, first-principles density functional theory calculations, Berry-phase polarization with phonon computations with density functional perturbation theory, we uncover a previously unrecognized polar A-type charge-disproportionation mode Q ACD that couples to the hybrid-improper trilinear polar mode Q Tri . This multimode interaction Q M ∼ Q Tri Q ACD lowers the symmetry to polar Pc within the C-type antiferromagnetic ordering and generates a rich phase space comprising polar metallic , semimetallic , and insulating ground states. A two-parameter Landau-type energy map E ( Q Tri , Q ACD ) reveals four symmetry-related polarization domains while both Q Tri and Q ACD set the direction of the spontaneous polarization. Q ACD controls a tunable electronic structure leading to insulator → metal

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