In addition to its metal-insulator transition (MIT), VO2 exhibits a rich phase behavior of insulating monoclinic (M1,M2) and triclinic (T) phases. By using micro-Raman spectroscopy and independent control of temperature and uniaxial strain in individual single-crystal microbeams, we map these insulating phases with their associated structural changes as represented by their respective phonon fr...

We demonstrate a novel pathway to control and stabilize oxygen vacancies in complex transition-metal oxide thin films. Using atomic layer-by-layer pulsed laser deposition (PLD) from two separate targets, we synthesize high-quality single-crystalline CaMnO3 films with systematically varying oxygen vacancy defect formation energies as controlled by coherent tensile strain. The systematic increase...

The dynamics of structural relaxation in a model polymer glass subject to spatially homogeneous, time-periodic shear deformation is investigated using molecular dynamics simulations. We study a coarse-grained bead-spring model of short polymer chains below the glass transition temperature. It is found that at small strain amplitudes, the segmental dynamics is nearly reversible over about 10^{4}...

Strain qualitatively changes the low-energy band structure of bilayer graphene, leading to the appearance of a pair of low-energy Dirac cones near each corner of the Brillouin zone, and a Lifshitz transition (a saddle point in the dispersion relation) at an energy proportional to the strain [Mucha-Kruczynski, Aleiner, and Fal’ko, Phys. Rev. B 84, 041404 (2011)]. Here, we show that in the vicini...

Biaxial compressive strain has been used to markedly enhance the ferroelectric properties of BaTiO3 thin films. This strain, imposed by coherent epitaxy, can result in a ferroelectric transition temperature nearly 500 degrees C higher and a remanent polarization at least 250% higher than bulk BaTiO3 single crystals. This work demonstrates a route to a lead-free ferroelectric for nonvolatile mem...

The activation strain or distortion/interaction model is a tool to analyze activation barriers that determine reaction rates. For bimolecular reactions, the activation energies are the sum of the energies to distort the reactants into geometries they have in transition states plus the interaction energies between the two distorted molecules. The energy required to distort the molecules is calle...

The ferroelastic phase transition and shape memory effect in La-modified lead zirconate titanate ferroelectric ceramics are demonstrated directly through the temperature-dependent macroscopic recoverable strain measured in a three-point bending configuration. X-ray diffraction measurements reveal that non- 180° domain switching occurs in the mechanically poled sample in two different ways at th...

We propose a Ginzburg-Landau phenomenological model for the dependence of the critical temperature on microscopic strain in tetragonal high-Tc cuprates. Such a model is in agreement with the experimental results for LSCO under epitaxial strain, as well as with the hydrostatic pressure dependence of Tc in most cuprates. In particular, a nonmonotonic dependence of Tc on hydrostatic pressure, as w...

Transition metal dichalcogenides (TMDCs), such as MoS2 and WSe2, provide two-dimensional atomic crystals with semiconductor band gap. In this work, we present a design of new mechano-electric generators and sensors based on transition metal dichalcogenide nanoribbon PN junctions and heterojunctions. The mechano-electric conversion was simulated by using a first-principle calculation. The output...

Order-disorder transitions are widely explored in various vortex structures condensed matter physics, i.e., the type-II superconductors and Bose-Einstein condensates. In this study, we have investigated ordering of polar phase (PZT)n/(STO)n superlattice systems through phase-field simulations. An antiorder state is discovered for short periodicity on an SSO substrate, owing to huge interfacial ...