相关论文: Ferroelectricity in twisted double bilayer graphen…
All known proper ferroelectrics are unable to polarize normal to a surface or interface if the resulting depolarization field is unscreened, but there is no fundamental principle that enforces this behavior. In this work, we introduce…
It was recently observed that materials showing most striking multiferroic phenomena are frustrated spin-density-wave magnets. We present a simple phenomenological theory, which describes the orientation of the induced electric polarization…
For the past few years, 2D ferroelectric materials have attracted strong interest for their potential in future nanoelectronics devices. The recent discovery of 2D ferroelectricity in twisted layers of insulating hexagonal boron nitride,…
We calculated a spin-polarized conductance in the almost unexplored nanostructure "high temperature ferromagnetic insulator/ graphene/ ferroelectric film" with a special attention to the impact of electric polarization rotation in a…
We present a theoretical investigation of the magnetic properties exhibited by twisted bilayer graphene (TBG) systems with small twist angles, where the appearance of flat minibands strongly enhances electron-electron interaction effects.…
Recent experimental discoveries of superconductivity and other exotic electronic states in twisted bilayer graphene (TBG) call for a reconsideration of our traditional theories of these states, usually based on the assumption of the…
The discovery of unconventional ferroelectric behavior in twisted bilayers has prompted the consideration of moir\'e heterostructures as polar materials. However, misconceptions about the nature and origin of the observed ferroelectricity…
Crystallography and dielectric properties in Dion-Jacobson layered perovskites, CsNdNb$_2$O$_7$ and RbNdNb$_2$O$_7$, have been examined in dense polycrystalline samples, and polarization hysteresis loops that substantiate ferroelectricity…
Sliding ferroelectricity was originally proposed to elucidate the out-of-plane polarization generated by a specific stacking arrangement of non-polar van der Waals layers. However, the concept of sliding ferroelectricity can be generalized…
Ferroelasticity describes a phenomenon in which a material exhibits two or more equally stable orientation variants and can be switched from one form to another under an applied stress. Recent works have demonstrated that two-dimensional…
Halide perovskites have emerged as promising materials for next-generation photovoltaics, laser sources and X-ray detectors. There is intense debate as to whether some photoactive halide perovskites exhibit ferroelectric behaviour and…
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 $R_{1/3}A_{2/3}\mathrm{FeO}_{2.67}$…
Particle-like topological structures such as skyrmions and vortices have garnered ever-increasing interests due to the rich physical insights and potential broad applications. Here we discover the reversible switching between polar skyrmion…
In twisted layered materials (t-LMs), an inter-layer rotation can break inversion symmetry and create an interfacial array of staggered out-of-plane polarization due to AB/BA stacking registries. This symmetry breaking can also trigger the…
The understanding of strongly-correlated materials, and in particular unconventional superconductors, has puzzled physicists for decades. Such difficulties have stimulated new research paradigms, such as ultra-cold atom lattices for…
Thermoelectric power of a material, typically governed by its band structure and carrier density, can be varied by chemical doping that is often restricted by solubility of the dopant. Materials showing large thermoelectric power are useful…
In stacks of two-dimensional crystals, mismatch of their lattice constants and misalignment of crystallographic axes lead to formation of moir\'{e} patterns. We show that moir\'{e} superlattice effects persist in twisted bilayer graphene…
Ferroelectric and two-dimensional materials are both heavily investigated classes of electronic materials. This is unsurprising since they both have superlative fundamental properties and high-value applications in computing, sensing etc.…
Topology and electron interactions are two central themes in modern condensed matter physics. Here we propose graphene based systems where both the band topology and interaction effects can be simply controlled with electric fields. We…
We theoretically show that an interlayer bias voltage in the AB-stacked bilayer graphene nanoribbons with armchair edges induces an electric polarization along the ribbon. Both tight-binding and ab initio calculations consistently indicate…