Reversible phase transformation of correlated oxides by field‐driven ionic process present opportunity to efficiently transduce between ionic transfer and electrical currents in insertion‐based reconfigurable transistors. However, the switching rate of insertion transistors is fundamentally limited by the slow rate of ionic insertion into the lattices of correlated oxides. Here, it is demonstrated that preformed oxygen vacancies in VO2−δ lattices strongly accelerate proton insertion by low gate voltage in synaptic transistors. As the degree of oxygen deficiency δ increases in VO2−δ transistors, the steepness of phase transformation and transconductance increase during the voltage sweep at the expense of the channel current modulation. Theoretical and experimental analyses reveal that the accelerated of H+ kinetics in the VO2−δ lattice occurs because immobile oxygen vacancies reduce the energy barrier to H+ migration. In an electronic synapse, this facile H+ migration in VO2−δ lattices renders “inscribed” memory by positioning the H+ neurotransmitter far from the electrolyte/VO2−δ interface. This discovery suggests a strategy to improve the learning and memory processes of artificial synaptic devices by controlling the density of intrinsic defects in the lattice framework to achieve efficient ion exchange.

We address the anisotropic oxygen diffusion in PrBaCo 2 O 5.5 using first-principles calculations based on the density functional theory. First, the experimentally observed magnetic properties such as ferromagnetic, ferrimagnetic, and paramagnetic phases are examined through systematic consideration of cobalt spin ordering and oxygen vacancy position. Then, the diffusion mechanism of an oxygen atom, assumed to be externally supplied, is explored by evaluating the oxygen migration barriers with the formation of one-dimensional oxygen-vacancy channel.

No abstract

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. prostrata is more widely used than E. alba. Morphological semblances have confounded identification of either species. Here, we report the complete chloroplast genomes of both species to provide an authentication system between the two species and understand their diversity. Both chloroplast genomes were 151,733-151,757 bp long and composed of a large single copy (83,285-83,300 bp), a small single copy (18,283-18,346 bp), and a pair of inverted repeats (25,075-25,063 bp). Gene annotation revealed 80 protein coding genes, 30 tRNA genes and four rRNA genes. A phylogenetic analysis revealed that the genus Eclipta is grouped with Heliantheae tribe species in the Asteraceae family. A comparative analysis verified 29 InDels and 58 SNPs between chloroplast genomes of E. prostrata and E. alba. The low chloroplast genome sequence diversity indicates that both species are really close to each other and are not completely diverged yet. We developed six DNA markers that distinguish E. prostrata and E. alba based on the polymorphisms of chloroplast genomes between E. prostrata and E. alba. The chloroplast genome sequences and the molecular markers generated in this study will be useful for further research of Eclipta species and accurate classification of medicinal herbs.

Atomistic defect engineering through the pulsed laser epitaxy of perovskite transition metal oxides offers facile control of their emergent opto‐electromagnetic and energy properties. Among the various perovskite oxides, EuTiO3 exhibits a strong coupling between the lattice, electronic, and magnetic degrees of freedom, which is highly susceptible to atomistic defects. In this study, we investigated the magnetic phase of EuTiO3 epitaxial thin films via systematic defect engineering. A magnetic phase transition from an antiferromagnet to a ferromagnet was observed when the unit cell volume of EuTiO3 expanded due to the introduction of Eu–O vacancies. Optical spectroscopy and density functional theory calculations show that the change in the electronic structure as the ferromagnetic phase emerges can be attributed to the weakened Eu–Ti–Eu super‐exchange interaction and the introduction of the ferromagnetic Eu–O–Eu interaction. Facile defect engineering in EuTiO3 thin films facilitates understanding and tailoring of their magnetic ground state.