相关论文: Ferroelectricity and topological vortices from mol…

There is great interest in hybrid organic-inorganic materials such as metal-organic frameworks (MOFs). The compounds [C(NH$_{2}$)$_{3}$]M(HCOO)$_{3}$, where M=Cu$^{2+}$ or Cr$^{2+}$ are Jahn-Teller (JT) active ions, are MOF with perovskite…

Density functional theory calculations have been performed for the structural, electronic, magnetic and ferroelectric properties of a mixed-valence Fe(II)-Fe(III) formate framework [NH$_2$(CH$_3$)$_2$][Fe$^{\rm III}$Fe$^{\rm II}$(HCOO)$_6$]…

Within the broad class of multiferroics (compounds showing a coexistence of magnetism and ferroelectricity), we focus on the subclass of "improper electronic ferroelectrics", i.e. correlated materials where electronic degrees of freedom…

The possibility to combine and finetune properties of functional molecular materials by chemical design is particularly relevant for organic ferroelectrics. In this work, we investigate a class of organic molecular materials that show…

Ferroic transition metal oxides, which exhibit spontaneous elastic, electrical, magnetic or toroidal order, exhibit functional properties that find use in ultrastable solid-state memories to sensors and medical imaging technologies. To…

The central goal of crystal engineering is to develop precise control over material function \emph{via} rational design of structure. A particularly successful realisation of this paradigm is the example of hybrid improper ferroelectricity…

Using first-principles methods, we predict the energy landscape and ferroelectric states of double perovskites of the form AA$'$BB$'$O$_6$ in which the atoms on both the A and B sites are arranged in rock-salt order. While we are not aware…

Fluid molecular ferroelectrics are a new class of organic materials where ferroelectricity is found in conjunction with 3D fluidity whilst still retaining spontaneous polarization values comparable to their traditional solid state…

We review the phenomenology of coupled magnetic and electric order parameters for systems in which ferroelectric and incommensurate magnetic order occur simultaneously. We discuss the role that such materials might play in fabricating novel…

Large electron-electron Coulomb-interactions in correlated systems can lead to a periodic arrangement of localized electrons, the so called "charge-order". The latter is here proposed as a driving force behind ferroelectricity in iron…

Using first-principles calculations, we predict that tunable ferroelectricity can be realized in oxide perovskites with the Grenier structure and ordered oxygen vacancies. Specifically, we show that $R_{1/3}A_{2/3}\mathrm{FeO}_{2.67}$…

Ferroelectric HfO$_2$ has emerged as a highly promising material for high-density nonvolatile memory and nanoscale transistor applications. However, the uncertain origin of polarization in HfO$_2$ limits our ability to fully understand and…

First-principles calculations are presented for the layered perovskite Ca$_3$Mn$_2$O$_7$. The results reveal a rich set of coupled structural, magnetic and polar domains in which oxygen octahedron rotations induce ferroelectricity,…

Ferroelectricity occurs in crystals with broken spatial inversion symmetry. In conventional perovskite oxides, concerted ionic displacements within a three-dimensional network of transition metal-oxygen polyhedra (MOx) manifest spontaneous…

There has been tremendous research activity in the field of magneto-electric (ME) multiferroics after Kimura et al. [1] showed that antiferromagnetic and ferroelectric order coexist in orthorhom- bically distorted perovskite TbMnO3 and are…

The family of molecular conductors TMTTF/TMTSF-X demonstrates almost all known electronic phases in parallel with a set of weak structural modifications of anion ordering and mysterious structureless transitions. Only in early 2000's their…

Ferroelectricity, a hallmark of spontaneous inversion-symmetry breaking, has been a central concept in condensed matter physics and functional materials research, yet recent discoveries are revealing that switchable polarization can emerge…

Metal-organic frameworks (MOFs) possess a hybrid nature, combining the inorganic properties from the metal ions and the organic properties from the molecular linkers. Stroppa, \textit{et al.}, showed that the perovskite-type MOF…

We explore via density functional calculations the magnetic doping of a topological ferroelectric as an unconventional route to multiferroicity. Vanadium doping of the layered perovskite La$_{2}$Ti$_{2}$O$_{7}$ largely preserves electric…

This letter addresses basic questions concerning ferroelectric order in positionally disordered dipolar materials. Three models distinguished by dipole vectors which have one, two or three components are studied by computer simulation.…