相关论文: Phase transitions and ferroelectricity in very thi…

We study ferroelectricity in thin films of pseudo-proper ferroelectrics such as the so-called spiral multiferroics. We find that this type of ferroelectricity stands better against depolarizing fields than conventional one. Its…

The finite screening length by real metallic electrodes, albeit very small (<1A), results in finite depolarizing field that tends to split the film into domains. In very thin ferroelectric films the domain structure reduces to sinusoidal…

According to a continuous medium theory, in very thin ferroelectric films with real metallic electrodes (or dead layers near the electrodes) the domain structure reduces to sinusoidal distribution of ferroelectric polarization. Such a…

We present molecular dynamics simulations of a realistic model of an ultrathin film of BaTiO$_3$ sandwiched between short-circuited electrodes to determine and understand effects of film thickness, epitaxial strain and the nature of…

We present the first analytical study of phase transitions in ferroelastic-ferroelectric epitaxial thin films on exactly solvable model. The emerging domain structure with domains of equal width (which may be exponentially large on a "soft"…

We simulate from first-principles the energetic, structural, and electronic properties of ferroelectric domains in ultrathin capacitors made of a few unit cells of BaTiO$_3$ between two metallic SrRuO$_3$ electrodes in short circuit. The…

Ferroelectric films usually have phase states and physical properties very different from those of bulk ferroelectrics. Here we propose free-standing ferroelectric-elastic multilayers as a bridge between these two material systems. Using a…

Understanding the dynamic behavior of the domain structure is critical to the design and application of super-elastic freestanding ferroelectric thin films. The phase-field simulation is currently a powerful tool for observing, exploring,…

We study the ferroelectric stability and surface structural properties of an oxygen-terminated hexagonal YMnO$_3$ ultra-thin film using density functional theory. Under an open circuit boundary condition, the ferroelectric state with the…

T.W. Noh and his group (Kim et al.: PRL, 2005) have recently published a seminal experimental study of very thin ferroelectric (FE) BaTiO3 capacitors. They found an evidence that all their samples, including the thinnest one (d=5 nm), are…

Nanoscale ferroelectric topologies such as vortices, anti-vortices, bubble patterns etc. are stabilized in thin films by a delicate balance of both mechanical and electrical boundary conditions. A systematic understanding of the phase…

We consider ferroelectric phase transitions in both short-circuited and biased ferroelectric-semiconductor films with a space (depletion) charge which leads to some unusual behavior. It is shown that in the presence of the charge the…

We study how the ferroelastic domain structure sets in in an epitaxial film of a material with second order proper ferroelastic transition. The domain structures considered are similar to either $a_{1}/a_{2}/a_{1}/a_{2}$ or $c/a/c/a$…

We report studies of ferroelectricity in ultra-thin perovskite films with realistic electrodes. The results reveal stable ferroelectric states in thin films less than 10 \AA thick with polarization normal to the surface. Under short-circuit…

Atomic-scale ferroelectrics are of great interest for high-density electronics, particularly field-effect transistors, low-power logic, and nonvolatile memories. We devised a film with a layered structure of bismuth oxide that can stabilize…

Thin ferromagnetic elements in the form of rectangular prisms are theoretically investigated in order to study the transition from single-domain to two-domain state, with changing the in-plane aspect ratio p. We address two main questions:…

Ferroelectricity has recently been demonstrated in germanium-based inorganic halide perovskites. We use atomistic first-principles-based simulations to study ultra-thin CsGeBr$_3$ films with thicknesses of 4-18 nm and develop a theory for…

A thermodynamic theory of ferroelectric thin film multilayers is developed. The free energy function is written down using a multilayer model in which c-domain layers of one ferroelectric material alternate with a-domain layers of a second…

We study the domain structure in ferroelectric thin films with a `passive' layer (material with damaged ferroelectric properties) at the interface between the film and electrodes within a continuous medium approximation. An abrupt…

The properties of a ferroelectric, (001)-oriented, thin film clamped to a substrate are investigated analytically and numerically. The emphasis is on the tetragonal, polydomain, ferroelectric phase, using a three domain structure, as is…