Effects of oxygen vacancy concentration and temperature on memristive behavior of SrRuO3/Nb:SrTiO3 junctions

Metal/semiconductor memristive heterostructures have potential applications in nonvolatile memory and computing devices.To enhance the performance of the memristive devices,it requires a comprehensive engineering to the metal/semiconductor interfaces.Here in this paper,we discuss the effects of oxygen vacancies and temperature on the memristive behaviors of perovskite-oxide Schottky junctions,each consisting of SrRuO3 thin films epitaxially grown on Nb:SrTiO3 substrates.The oxygen partial pressure and laser fluence are controlled during the film growth to tune the oxygen defects in SrRuO3 films,and the Schottky barrier height can be controlled by both the temperature and oxygen vacancies.The resistive switching measurements demonstrate that the largest resistance switching ratio can be obtained by controlling oxygen vacancy concentration at lower temperature.It suggests that reducing Schottky barrier height can enhance the resistive switching performance of the SrRuO3/Nb:SrTiO3 heterostructures.This work can conduce to the development of high-performance metal-oxide/semiconductor memristive devices.

Epitaxial growth of highly strained antimonene on Ag（111）

The synthesis of antimonene, which is a promising group-V 2D material for both fundamental studies and technological applications, remains highly challenging. Thus far, it has been synthesized only by exfoliation or growth on a few substrates. In this study, we show that thin layers of antimonene can be grown on Ag（111） by molecular beam epitaxy. High-resolution scanning tunneling microscopy combined with theoretical calculations revealed that the submonolayer Sb deposited on a Ag（111） surface forms a layer of AgSb2 surface alloy upon annealing. Further deposition of Sb on the AgSb2 surface alloy causes an epitaxial layer of Sb to form, which is identified as antimonene with a buckled honeycomb structure. More interestingly, the lattice constant of the epitaxial antimonene （5 /-） is much larger than that of freestanding antimonene, indicating a high tensile strain of more than 20%. This kind of large strain is expected to make the antimonene a highly promising candidate for room- temperature quantum spin Hall material.

Observation of pseudogap in SnSe2 atomic layers grown on graphite

Superconducting metal dichalcogenides(MDCs)present several similarities to the other layered SI1-perconductors like cuprates.The superconductivity in atomically thin MDCs has been demonstrated by recent experiments,however,the investigation of the superconductivity intertwined with other or-ders are scarce.Investigating the pseudogap in atomic layers of MDCs may help to understand the superconducting mechanism for these true two dimensional(2D)superconducting systemns.Herein we report a pseudogap opening in the tunneling spectra of thin layers of SnSe2 epitaxially grown on highly oriented pyrolytic graphite(HOPG)with scanning tunneling microscopy/spectroscopy(STM/STS).A significant V-shaped pseudogap was observed to open near the Fermi level(Er)in the sTS.And at elevated temperatures,the gap gradually evolves to a shallow dip.Our experimental observations provide direct evidence of a pseudogap state in the electron-doped SnSe2 atomic layers on the HOPG surface,which may stimulate further exploration of the mechanism of superconductivity at 2D limit in MDCs.