Molecular Dynamics Simulations of Structural Changes for a Molten Ag54Cu1 Cluster during Cooling

Structural changes of an Ag54Cu1 cluster had been computationally studied by molecular dynamics approaches. Packing transition was demonstrated by analytical tools including potential energy, atomic density profiles, and shape factor as well as visually packing images. During the process of temperature decreasing, this cluster preferentially assumes icosahedral geometry. Copper atom usually has an atomic position inside a cluster. As temperature decreases, its position will change. Potential energy shows different temperature regimes in the structural transformation. Atomic density profile gives packing pattern in different region. Shape factor presents the morphology changes of this cluster.

Break of symmetry at the surface of IrTe2 upon phase transition measured by X-ray photoelectron diffraction

IrTe2 undergoes a series of charge-ordered phase transitions below room temperature that are characterized by the formation of stripes of Ir dimers of different periodicities. Full hemispherical X-ray photoelectron diffraction (XPD) experiments have been performed to investigate the atomic position changes undergone near the surface of 1T−IrTe2 in the first-order phase transition, from the (1 × 1) phase to the (5 × 1) phase. Comparison between experiment and simulation allows us to identify the consequence of the dimerization on the Ir atoms local environment. We report that XPD permits to unveil the break of symmetry of IrTe2 trigonal to a monoclonic unit cell and confirm the occurence of the (5 × 1) reconstruction within the first few layers below the surface with a staircase-like stacking of dimers.

Strain-driven autonomous control of cation distribution for artificial ferroelectrics

In past few decades, there have been substantial advances in theoretical material design and experimental synthesis, which play a key role in the steep ascent of developing functional materials with unprecedented properties useful for next-generation technologies. However, the ultimate goal of synthesis science, i.e., how to locate atoms in a specific position of matter, has not been achieved. Here, we demonstrate a unique way to inject elements in a specific crystallographic position in a composite material by strain engineering. While the use of strain so far has been limited for only mechanical deformation of structures or creation of elemental defects, we show another powerful way of using strain to autonomously control the atomic position for the synthesis of new materials and structures. We believe that our synthesis methodology can be applied to wide ranges of systems, thereby providing a new route to functional materials.

Interface polarization model for a 2-dimensional electron gas at the BaSnO3/LaInO3 interface

In order to explain the experimental sheet carrier density n2D at the interface of BaSnO3/LaInO3, we consider a model that is based on the presence of interface polarization in LaInO3 which extends over 2 pseudocubic unit cells from the interface and eventually disappears in the next 2 unit cells. Considering such interface polarization in calculations based on 1D Poisson-Schrödinger equations, we consistently explain the dependence of the sheet carrier density of BaSnO3/LaInO3 heterinterfaces on the thickness of the LaInO3 layer and the La doping of the BaSnO3 layer. Our model is supported by a quantitative analysis of atomic position obtained from high resolution transmission electron microscopy which evidences suppression of the octahedral tilt and a vertical lattice expansion in LaInO3 over 2–3 pseudocubic unit cells at the coherently strained interface.

Decohering power of thermal fluctuating electromagnetic field with a boundary

In this paper, we analyze the decohering power behaviors for an atom immersed in a thermal bath of fluctuating electromagnetic field in the presence of a perfectly reflecting plane boundary. Firstly, we analytically solve the master equation that governs the system evolution. Then, we discuss the behaviors of decohering power for an atom affected by thermal fluctuating electromagnetic field. It is found that the behaviors of decohering power are dependent on the field temperature, atomic position and polarization. Decohering power fluctuates to relatively stable values with the increasing atom’s distance from the boundary, which suggests a possible way of detecting the vacuum fluctuating and boundary effect. Additional conditions on the electromagnetic field give one more freedom to manipulate the variations of decohering power. Decohering power variations can efficiently reflect the behaviors of quantum coherence affected by electromagnetic vacuum fluctuation, and it is shown that quantum coherence can be effectively enhanced with the presence of a reflecting boundary.