Symmetry Considerations on Martensitic Transformations: "Ferroelectric" Metals?

Anderson, P. W.; Blount, E. I.

doi:10.1103/physrevlett.14.217

Cited by 508 publications

(328 citation statements)

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“…Although compositional ordering may be an obvious route to lift inversion symmetry, we recognize that experimentally in practice it may be challenging to achieve it, especially in oxide materials owing to bond-coordination requirements; therefore, although the route is simple, it is by no means straightforward. The design methodology demonstrated here implements method (3). Note that all materials are expected to show some interesting physical properties enabled by an acentric crystal structure with itinerant electrons, independent of the mechanism leading to the mutual coexistence of the prerequisite atomic and electronic structure.…”

Section: Resultsmentioning

confidence: 99%

“…In spite of the incompatibility between acentricity and metallicity, metallic materials that break the spatial parity operation mapping ðx; y; zÞ ! ðx; y; zÞ were originally discussed in the 1960s by Matthias and then, later more rigorously by Anderson and Blount 3 . The first experimental identification 4 of a candidate polar metal, the binary intermetallic V 2 Hf, was made a decade later.…”

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Designing a robustly metallic noncenstrosymmetric ruthenate oxide with large thermopower anisotropy

2014

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The existence of B30 noncentrosymmetric metals (NCSM) suggests a contraindication between crystal structures without inversion symmetry and metallic behaviour. Those containing oxygen are especially scarce. Here we propose and demonstrate a design framework to remedy this property disparity and accelerate NCSM oxide discovery. The primary ingredient relies on the removal of inversion symmetry through displacements of atoms whose electronic degrees of freedom are decoupled from the states at the Fermi level. Density functional theory calculations validate this crystal-chemistry strategy, and we predict a new polar ruthenate exhibiting robust metallicity. We demonstrate that the electronic structure is unaffected by the inclusion of spin-orbit interactions, and that cation-ordered SrCaRu 2 O 6 exhibits a large thermopower anisotropy (|DS > |B6.3 mV K À 1 at 300 K) derived from its polar structure. Our findings provide chemical and structural selection guidelines to aid in the search of NCSM with enhanced thermopower anisotropy.

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Section: Resultsmentioning

confidence: 99%

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Designing a robustly metallic noncenstrosymmetric ruthenate oxide with large thermopower anisotropy

2014

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“…As an interesting problem, the axial ratio (c/a) of the indium alloys containing solute atoms such as Cd, Hg, Sn and Pb has been found to change depending on the electron atom ratio Yonemitsu et al (4) (5) have shown that the decrease of Fermi energy due to tetragonal distortion is the origin of phase transition in the indium alloy. Anderson et al (6) have explained the cubic-tetragonal transition in alloys by applying Landau's theory of phase transition(7). However, detailed analysis has not been reported in their paper (6).…”

Section: Introductionmentioning

confidence: 99%

Phenomenological Theory of Phase Change from <I>FCC</I> to <I>FCT</I> in the Indium Alloy

Kachi

1975

Trans. JIM

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In-TI alloy transforms from fcc to fct when the TI composition becomes lower than about 23 at%. In the In-Hg and the In-Pb alloys, fcc, fct(c/a>1) and fct(c/a<1) phases appear and the axial ratio (c/a) is dependent on the electron atom ratio. These phase changes in the indium alloys are treated by the phenomenological theory based on the Landau's theory of phase transition, by assuming that the elastic constant (C11-C12)/2 of the fcc phase is directly proportional to composition m and becomes zero at m=m0. As a result, composition dependences of the axial ratio (c/a) and (C11-C12)/2 in both fcc and fct phases are well explained phenomenologically.

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“…It relies on tuning the degree of correlation of the recently discovered class of materials referred to as 'ferroelectric metals' with LiOsO 3 as the prototypical member [10]. This material is the first undisputed realization of the Anderson-Blount mechanism [11], and challenges the expectation that conduction electrons in metals would screen the electric field induced by polar displacements [10,12,13]. Despite robust metallicity, this material shares structural similarities with prototypical insulating ferroelectric oxides, such as LiNbO 3 [14,15]: A R3c crystal structure with acentric cation displacements and distorted OsO 6 octahedra [16,17] and comparable lattice parameters [10,14].…”

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Design of a Mott Multiferroic from a Nonmagnetic Polar Metal

et al. 2015

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We examine the electronic properties of newly discovered "ferroelectric" metal LiOsO3 combining density-functional and dynamical mean-field theories. We show that the material is close to a Mott transition and that electronic correlations can be tuned to engineer a Mott multiferroic state in 1/1 superlattice of LiOsO3 and LiNbO3. We use electronic structure calculations to predict that the (LiOsO3)1/(LiNbO3)1 superlattice is a type-I multiferroic material with a ferrolectric polarization of 41.2 µC cm −2 , Curie temperature of 927 K, and Néel temperature of 671 K. Our results support a route towards high-temperature multiferroics, i.e., driving non-magnetic polar metals into correlated insulating magnetic states. Introduction.-Multiferroics (MF) are a class of insulating materials where two (or more) primary ferroic order parameters, such as a ferroelectric polarization and long-range magnetic order, coexist. Technologically, they offer the possibility to control magnetic polarizations with an electric field for reduced power consumption [1, 2]. Nonetheless, intrinsic room-temperature MF remain largely elusive. This fact may be understood by examining the microscopic origins for the ferroic order which aids in classifying different phases: In Type-I MF, ferroelectricity and magnetism arise from different chemical species with ordering temperatures largely independent of one another and weak magnetoelectric (ME) coupling [3]. The ferroelectric ordering also typically appears at temperatures higher than the magnetic order, and the spontaneous polarization P is large since it is driven by a second-order Jahn-Teller distortion, e.g., BiFeO 3 [3, 4]. In Type-II MF, however, magnetic order induces ferroelectricity, which indicates a strong ME coupling between the two order parameters. Nonetheless, P is usually much smaller, e.g., by a factor of 10 2 as in R-Mn 2 O 5 (R being rare earth) [5]. In a few MFs with high-transition temperatures, i.e., BiFeO 3 [6] and Sr 1−x Ba x MnO 3 [7-9], magnetism is caused by Mott physics arising from strong correlations. The interactions localize the spins at high temperature, paving the way for magnetic ordering at room temperature. Materials where this robust magnetism is coupled with ferroelectric distortions are ideal candidates for a room-temperature MFs.

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Symmetry Considerations on Martensitic Transformations: "Ferroelectric" Metals?

Cited by 508 publications

References 7 publications

Designing a robustly metallic noncenstrosymmetric ruthenate oxide with large thermopower anisotropy

Designing a robustly metallic noncenstrosymmetric ruthenate oxide with large thermopower anisotropy

Phenomenological Theory of Phase Change from <I>FCC</I> to <I>FCT</I> in the Indium Alloy

Design of a Mott Multiferroic from a Nonmagnetic Polar Metal

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