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Elevating the temperature needed to realize the quantum anomalous Hall effect (QAHE) to above 77 K or higher is the key to practical applications of the effect as well as many others based on it. Here, we briefly review the recent progresses, especially the experimental ones, on searching for magnetic topological insulators that can exhibit the QAHE at higher temperature. Based on our understanding of these results, we will give the principles and roadmap for designing and constructing high-temperature quantum anomalous Hall systems. [ABSTRACT FROM AUTHOR]

It has been 30 years since the Nobel Prize was awarded for scanning tunneling microscope (STM) in the year 1986, and there have been many instrumental developments and experimental achievements based on STM. In consideration of the strong capability and the extreme versatility in imaging, manipulating, and spectroscopy at the atomic level, STM has witnessed remarkable breakthroughs in many disciplines of condensed matter physics. In this paper, we will focus on recent STM studies on the interface superconductivity, which demonstrate a novel platform for exploring two dimensional superconductors and even high temperature superconductors by means of interface engineering. [ABSTRACT FROM AUTHOR]

The photoabsorption edge shifting from UV to visible region accompanied with increased intensity and Raman features change was observed for N+ implanted TiO2. Raman spectra prove the formation of TiNx and oxygen vacancies in the implanted TiO2, which is considered as the origin of absorption edge shifting. The work may give a hint to increase the photocatalytic activity of TiO2 in the visible region at the molecule level. [ABSTRACT FROM AUTHOR]

Ultra-thin Pb films with magic thicknesses of 2 monolayer (ML), 4 ML and 6 ML were prepared of atomically flat on the substrate of Si(111)-α-√3 × √3 (or SIC phase) at 145 K. Their surface morphologies and stability were studied by low temperature scanning tunneling microscopy and temperature-dependent angle resolved photoemission spectroscopy. We found that the well ordered SIC interface can lower the diffusion barrier and enhance the interface charge transfer, leading to different critical thickness compared to Pb/Si(111)-7 × 7 grown under same conditions. Enhanced thermal expansion coefficients were also observed in ultra-thin Pb films at low temperature. [ABSTRACT FROM AUTHOR]

We have studied the superconductivity of Pb ultra-thin films with thickness from 1 monolayer (ML) to 7 ML grown on Si(111) by molecular beam epitaxy. In situ low temperature scanning tunneling spectroscopy (STS) and angle-resolved photoemission spectroscopy (ARPES) measurements were performed on the films. It is suggested that the interface effect plays a critical role in enhancing the electron-phonon coupling, which consequently increases the superconducting transition temperature when a film reaches to the two-dimensional limit. [ABSTRACT FROM AUTHOR]