Electronic Structure of Few-Layer Black Phosphorus from μ-ARPES.

Black phosphorus (BP) stands out among two-dimensional (2D) semiconductors because of its high mobility and thickness dependent direct band gap. However, the quasiparticle band structure of ultrathin BP has remained inaccessible to experiment thus far. Here we use a recently developed laser-based microfocus angle resolved photoemission (μ-ARPES) system to establish the electronic structure of 2-9 layer BP from experiment.

Break of symmetry at the surface of IrTeupon phase transition measured by x-ray photoelectron diffraction.

IrTeundergoes a series of charge-ordered phase transitions below room temperature that are characterized by the formation of stripes of Ir dimers of different periodicities. Full hemispherical x-ray photoelectron diffraction (XPD) experiments have been performed to investigate the atomic position changes undergone near the surface of 1-IrTein the first-order phase transition, from the (1 × 1) phase to the (5 × 1) phase. Comparison between experiment and simulation allows us to identify the consequence of the dimerization on the Ir atoms local environment.

Synthetic control over polymorph formation in the d-band semiconductor system FeS.

Pyrite, also known as fool's gold is the thermodynamic stable polymorph of FeS. It is widely considered as a promising d-band semiconductor for various applications due to its intriguing physical properties. Marcasite is the other naturally occurring polymorph of FeS.

Superconductivity with High Upper Critical Field in the Cubic Centrosymmetric η-Carbide NbRhC.

The upper critical field is a fundamental measure of the strength of superconductivity in a material. It is also a cornerstone for the realization of superconducting magnet applications. The critical field arises because of the Cooper pair breaking at a limiting field, which is due to the Pauli paramagnetism of the electrons.

CoO microspheres and metallic Co evolved from hexagonal α-Co(OH) plates in a hydrothermal process for lithium storage and magnetic applications.

CoO microspheres and metallic Co could be successfully synthesized by simply reacting cobalt acetate with a mixture solvent of ethylene glycol and deionized water in a hydrothermal process for different times. As the reaction proceeded, α-Co(OH), CoO and metallic Co were produced. To understand the phase evolution processes from α-Co(OH) to CoO and then metallic Co, a range of time-dependent experiments were carried out, and the intermediate products obtained at different reaction times were investigated in detail.

Free-standing α-Co(OH)2/graphene oxide thin films fabricated through delamination and reassembling of acetate anions intercalated α-Co(OH)2 and graphene oxide in water.

A novel hydrothermal process is demonstrated to prepare acetate anions intercalated α-Co(OH)2 that can be delaminated in water without any additional anion exchange processes. Positively charged Co(OH)2 nanosheets with lateral size of hundreds of nanometers and thickness less than 2 nm can be obtained by dispersing the as-obtained α-Co(OH)2 into water followed by sonication. The exfoliated Co(OH)2 nanosheets can be restacked into its original structure with different interlayer d-spacings.