Abstract
The recent discovery of "polar metals" with ferroelectriclike displacements offers the promise of designing ferroelectrics with tunable energy gaps by inducing controlled metal-insulator transitions. Here we employ first-principles calculations to design a metallic polar superlattice from nonpolar metal components and show that controlled intermixing can lead to a true insulating ferroelectric with a tunable band gap. We consider a 2/2 superlattice made of two centrosymmetric metallic oxides, La0.75Sr0.25MnO3 and LaNiO3, and show that ferroelectriclike displacements are induced. The ferroelectriclike distortion is found to be strongly dependent on the carrier concentration (Sr content). Further, we show that a metal-to-insulator (MI) transition is feasible in this system via disproportionation of the Ni sites. Such a disproportionation and, hence, a MI transition can be driven by intermixing of transition metal ions between Mn and Ni layers. As a result, the energy gap of the resulting ferroelectric can be tuned by varying the degree of intermixing in the experimental fabrication method.
Original language | English |
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Article number | 177603 |
Journal | Physical Review Letters |
Volume | 119 |
Issue number | 17 |
DOIs | |
State | Published - Oct 25 2017 |
Funding
This work was supported by Department of Energy Grant No. DE- FG02-09ER46554 (S. G., S. T. P.) and by the Department of Energy Basic Energy Sciences, Materials Science and Engineering Directorate (A. Y. B.). The authors acknowledge the NERSC supercomputing facility for providing computer time. Authors acknowledge the Oak Ridge Leadership Computing Facility for providing computation time on “Titan” supercomputer under Grant No. “Mat136”, titled “Engineering multifunctionality in oxide heterostructure”.