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

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 BiPbTi 2 O 6 can crystallize in three polar and metallic structures, which can be transformed between via pressure or strain. In a heterostructure of layered BiPbTi 2 O 6 and PbTiO 3 , multiple states with different relative orientations of BiPbTi 2 O 6 polar displacements, and PbTiO 3 polarization, can be stabilized. At room temperature, the interfacial coupling enables electric fields to first switch PbTiO 3 polarization and subsequently drive 180°change of BiPbTi 2 O 6 polar displacements. At low temperatures, the heterostructure provides a tunable tunnelling barrier and might be used in multi-state memory devices.

Investigation into Cation-Ordered Magnetic Polar Double Perovskite Oxides

“…The focus of this quest mostly lay in identifying polar magnetic insulators (multiferroic and magnetoelectric systems). − However, following the prediction made by Anderson and Blount in 1965 regarding the possible existence of ferroelectric distortion in a metal and the subsequent observation of ferroelectric phase in LiOsO 3 in 2014, a recent surge of interests has developed in the direction of polar metals. A good number of complex oxide materials have experimentally reported to show − and theoretically predicted to exhibit − polar metallic behavior. Of these materials, however, a very few are magnetic in nature.…”

Coupled magnetic and structural phase transitions in the antiferromagnetic polar metal Pb2CoOsO6 under pressure

“…However, a metal that possesses both polar displacements and magnetization and most importantly a coupling between the two is extremely rare. Previous theoretical proposals of cation-ordered SrCaRu 2 O 6 9 and BiPbTi 2 O 6 17 show the coexistence of ferromagnetism with polar displacements but there is no strong coupling between the two properties.…”

“…Insulating materials which possess both electric polarization and magnetization and possibly a coupling between the two order parameters are called multiferroics, which has been an active research field in condensed matter physics and materials science 4-6 . On the other hand, materials with both polar displacements and intrinsic metallicity are termed as "polar metals" 3,7 , which have attracted increasing interest in experiment and theory [8][9][10][11][12][13][14][15][16][17] . Accordering to Anderson and Blount 3 , polar metals are characterized by a second-order structural phase transition with the appearance of a polar axis and the loss of inversion symmetry at a finite temperature.…”

Polar Metals Taxonomy for Materials Classification and Discovery

“…Namely, a thin polar metal film is deposited on a FE with low lattice mismatch. An external electric field switches the FE substrate and the resulting strain switches the polar metal [30,78]. This approach might be considered a variation of the ferroelastic switching mechanism, as both approaches use the unscreened strain field to switch polarization.…”