Engineering of Electron Confinement through Defect‐Based Localized Polarization on SrTiO₃ Surface

Abstract

Electron behaviors are expected to differ in circumstances with polarization. Changes in electron dynamics further result in changes in the physical properties, especially at reduced dimensions. In this paper, threshold photoemission is used to image a 2D electron gas induced on a SrTiO3 surface with regions polarized by defect‐based localized dipolar moments. It is found that the induction of surface polarization results in decrease of the surface itinerant electron density and the magnetic moments at room temperature. Such effects are attributed to the polarization‐based trapping of the surface itinerant electrons. It is also demonstrated that those changes induced by surface polarization can be manipulated by varying temperature. These findings address the importance of polarization in low‐dimensional electron dynamics, which offers an alternative way to engineer the properties of the SrTiO3‐based 2D electron gas.

Manipulation of the Bilateral Electron Transport across a Graphdiyne-Based Heterostructure

“…Each time, the sample is heated to the given temperature via a filament installed in the sample holder and then left to cool down to room temperature prior to the measurement. As shown in Figure e, there is a significant rise of PE after annealing at temperatures higher than 600 K. This results from the depletion of lattice oxygen in NiO, according to previous reports. , It has been revealed that the defect density at the TMO surface is much higher than that at the bulk, and these defects would significantly affect the electron behaviors around the surface. , As shown in Figure f,g, after the UHV annealing, τ 1 decreases from 0.86 to 0.56 ps, while τ 2 increases to 0.49 ps. Since oxygen vacancies in NiO are located deeply in the band gap, they are expected to act as trap states, causing the relaxation of excited electrons at higher energy levels.…”

“…39,40 It has been revealed that the defect density at the TMO surface is much higher than that at the bulk, and these defects would significantly affect the electron behaviors around the surface. 29,41 As shown in Figure 3f,g, after the UHV annealing, τ 1 decreases from 0.86 to 0.56 ps, while τ 2 increases to 0.49 ps. Since oxygen vacancies in NiO are located deeply in the band gap, they are expected to act as trap states, causing the relaxation of excited electrons at higher energy levels.…”

Oxygen Hole Character and Lateral Homogeneity in PrNiO2+δ Thin Films

“…40 nm at room temperature [27]. Further, domains in the SrTiO 3 surface polarization [28] originating from local defects, studied with PEEM using a 400 nm-sized beam revealed polarized regions with sizes of several μm. Consequently, we argue that possible spatial variations of our reduced samples within these typical length scales should have been visible in our study, and hence this points again towards a laterally homogeneous topotactical reduction.…”

Near‐Field Plasmons Imaging and Energy Analysis on Bi2Te3 Film

“…Photoemission electron microscope (PEEM) has ultra-high spatio-temporal resolution to study the surface properties of materials with nontouching technology. [55][56][57][58] The spatial resolution is sub-10 nm, the temporal resolution is sub-5 fs, and the energy resolution is about 100 meV. In our work, PEEM is used to observe the near-field plasmon modes distribution and the material emitted electronic kinetic energy distribution.…”