Nanjing University

About: Nanjing University is a education organization based out in Nanjing, China. It is known for research contribution in the topics: Catalysis & Adsorption. The organization has 85961 authors who have published 105504 publications receiving 2289036 citations. The organization is also known as: NJU & Nanking University.

Graphene and related two-dimensional materials: Structure-property relationships for electronics and optoelectronics

Abstract: The exfoliation and identification of the two-dimensional (2D) single atomic layer of carbon have opened the opportunity to explore graphene and related 2D materials due to their unique properties. 2D materials are regarded as one of the most exciting solutions for next generation electronics and optoelectronics in the technological evolution of semiconductor technology. In this review, we focus on the core concept of “structure-property relationships” to explain the state-of-the-art of 2D materials and summarize the unique electrical and light-matter interaction properties in 2D materials. Based on this, we discuss and analyze the structural properties of 2D materials, such as defects and dopants, the number of layers, composition, phase, strain, and other structural characteristics, which could significantly alter the properties of 2D materials and hence affect the performance of semiconductor devices. In particular, the building blocks principles and potential electronic and optoelectronic applications...

Structural transformation and ferroelectromagnetic behavior in single-phase Bi1−xNdxFeO3 multiferroic ceramics

Abstract: Single-phase Bi1−xNdxFeO3 (BNFOx) (x=0–02) multiferroic ceramics were prepared to study the effects of Nd substitution on their crystal structure and ferroelectromagnetic behavior Rietveld refinement of x-ray diffraction data showed a continual transformation of crystal structure from the rhombohedral structure of BNFOx=0 (BiFeO3) to a triclinic structure in BNFOx=005–015 and a pseudotetragonal structure in BNFOx=0175–02 Ferroelectromagnetic measurements revealed the existence of ferroelectricity with remnant polarization of ∼9μC∕cm2 in BNFOx=0–0175, paraelectricity in BNFOx=02, and weak ferromagnetism with remnant magnetizations of 007–0227emu∕g in BNFOx=015–02 Magnetoelectric coupling was obvious in BNFOx=015–0175 near the Neel temperature of ∼380°C

Correlated electronic phases in twisted bilayer transition metal dichalcogenides

Abstract: In narrow electron bands in which the Coulomb interaction energy becomes comparable to the bandwidth, interactions can drive new quantum phases. Such flat bands in twisted graphene-based systems result in correlated insulator, superconducting and topological states. Here we report evidence of low-energy flat bands in twisted bilayer WSe2, with signatures of collective phases observed over twist angles that range from 4 to 5.1°. At half-band filling, a correlated insulator appeared that is tunable with both twist angle and displacement field. At a 5.1° twist, zero-resistance pockets were observed on doping away from half filling at temperatures below 3 K, which indicates a possible transition to a superconducting state. The observation of tunable collective phases in a simple band, which hosts only two holes per unit cell at full filling, establishes twisted bilayer transition metal dichalcogenides as an ideal platform to study correlated physics in two dimensions on a triangular lattice. Tunable correlated states are observed in twist bilayer WSe2 over a range of twist angles, with signatures of superconductivity for a twist of 5.1°.

Two-Photon-Pumped Perovskite Semiconductor Nanocrystal Lasers.

Abstract: Two-photon-pumped lasers have been regarded as a promising strategy to achieve frequency up-conversion for situations where the condition of phase matching required by conventional approaches cannot be fulfilled. However, their practical applications have been hindered by the lack of materials holding both efficient two-photon absorption and ease of achieving population inversion. Here, we show that this challenge can be tackled by employing colloidal nanocrystals of perovskite semiconductors. We observe highly efficient two-photon absorption (with a cross section of 2.7 × 106 GM) in toluene solutions of CsPbBr3 nanocrystals that can excite large optical gain (>500 cm–1) in thin films. We have succeeded in demonstrating stable two-photon-pumped lasing at a remarkable low threshold by coupling CsPbBr3 nanocrystals with microtubule resonators. Our findings suggest perovskite nanocrystals can be used as excellent gain medium for high-performance frequency-up-conversion lasers toward practical applications.