# Design of a multifunctional polar metal via first-principles high-throughput structure screening

## TL;DR

This paper predicts a new polar metal, BiPbTi2O6, using high-throughput first-principles screening, demonstrating its potential for multi-state memory devices through strain, pressure, and heterostructure engineering.

## Contribution

It introduces a novel polar metal predicted via computational screening, with tunable properties in bulk and heterostructure forms, expanding the design space for functional polar metals.

## Key findings

- BiPbTi2O6 can crystallize in three polar metallic structures.
- Heterostructures enable electric-field-driven switching of polar states.
- Potential application in multi-state memory devices.

## Abstract

Intrinsic polar metals are rare, especially in oxides, because free electrons screen electric fields in a metal and eliminate the internal dipoles that are needed to break inversion symmetry. Here we use first-principles high-throughput structure screening to predict a new polar metal in bulk and thin film forms. After screening more than 1000 different crystal structures, we find that ordered BiPbTi2O6 can crystallize in three polar and metallic structures, which can be transformed between via pressure or strain. In a heterostructure of layered BiPbTi2O6 and PbTiO3, multiple states with different relative orientations of BiPbTi2O6 polar displacements, and PbTiO3 polarization, can be stabilized. At room temperature, the interfacial coupling enables electric fields to first switch PbTiO3 polarization and subsequently drive 180{\deg} change of BiPbTi2O6 polar displacements. At low temperatures, the heterostructure provides a tunable tunnelling barrier and might be used in multi-state memory devices.