Related papers: Chirality in BaTiOCu$_4$(PO$_4$)$_4$
Multiferroics, showing simultaneous ordering of electrical and magnetic degrees of freedom, are remarkable materials as seen from both the academic and technological points of view. A prominent mechanism of multiferroicity is the…
Vector-chiral (VC) antiferromagnetism is a spiral-like ordering of spins which may allow ferroelectricity to occur due to loss of space inversion symmetry. In this paper we report direct experimental observation of ferroelectricity in the…
Noncollinear ferroic materials are sought after as testbeds to explore the intimate connections between topology and symmetry, which result in electronic, optical and magnetic functionalities not observed in collinear ferroic materials. For…
Ferroic magnetic quadrupole order exhibiting macroscopic magnetoelectric activity is discovered in the novel compound $A$(TiO)Cu$_4$(PO$_4$)$_4$ with $A$ = Pb, which is in contrast with antiferroic quadrupole order observed in the…
In this short article, we overview a concept of electronic toroidal multipoles, and their ordering with associated physical properties in non-magnetic and magnetic materials. The toroidal multipoles are introduced as microscopic electronic…
Ferroics, characterized by a broken symmetry state with nonzero elastic, polar, or magnetic order parameters $\vec{u}$, are recognized platforms for staging and manipulating topologically-protected structures as well as for detecting…
Ferroelectricity in BaTiO3 was observed nearly eighty years ago, but the mechanism underlying its ferroelectric-paraelectric phase transition remains elusive. The order-disorder transition has been recognized as playing a critical role,…
In this letter, we report the structural, electronic and ferroelectric properties of the layered mixed-valent transition-metal compound, Sr$_{4}$Fe$_{6}$O$_{12}$ (SFO). We demonstrate how SFO undergoes a phase transition from a…
In solid state physics, any phase transition is commonly observed as a change in the microscopic distribution of charge, spin, or current. Here we report the nature of an exotic order parameter inherent in the localized electron orbitals…
Ferroelectric nematic liquid crystals are formed by achiral molecules with large dipole moments. Its three-dimensional orientational order is universally described as unidirectionally polar. We demonstrate that the ground state of…
General microscopic mechanism of ferroelectric ordering in chiral smectic C* liquid crystals is considered. It is shown that if the mesogenic molecules have a sufficiently low symmetry, the spontaneous polarization is proportional to one of…
From a symmetry perspective, ferroaxial order belongs to the same symmetry as time-reversal-even pseudovectors. Experimentally, ${\rm K_2Zr(PO_4)_2}$ is known to undergo a displacive-type phase transition from a non-ferroaxial to a…
The chiral source and its mechanism in the molecular system are of great significance in many fields. In this work, we proposed visualized methods to investigate physical mechanism of chiral molecule, where the electric and magnetic…
We report a ferroelectric order at ~ 98 K for NiFe2O4, which carries an inverse spinel structure with a centrosymmetric Fd3m structure at room temperature. The value of spontaneous electric polarization is considerably high as ~ 0.29…
We study the electrical behavior of multiferroic BiFeO$_3$ by means of first-principles calculations. We do so by constraining a specific component of the electric displacement field along a variety of structural paths, and by monitoring…
Recent experiments have found a bent-core liquid crystal in which the layer chirality alternates from layer to layer, giving a racemic or "antichiral" material, even though the molecules are uniformly chiral. To explain this effect, we map…
Although ferroelectric materials are characterised by their parallel arrangement of electric dipoles, in the right boundary conditions these dipoles can reorganize themselves into vortices, antivortices and other non-trivial topological…
Based on a symmetry approach, we propose a possible explanation of the weak ferromagnetic component recently observed in YBaCo$_3$FeO$_7$ (Valldor et al. Phys Rev B, $\bf {84}$ 224426 (2011)) and other isostructural compounds in the…
We present a general, systematic theory of electromagnetism and chirality in crystalline solids. Symmetry is its basic guiding principle, enabling us to consider macroscopic multipole densities without reference to any specific microscopic…
We present a general formalism of multipole descriptions under the space-time inversion group. We elucidate that two types of atomic toroidal multipoles, i.e., electric and magnetic, are fundamental pieces to express electronic order…