Haijun Bu

Discovery of a new type of topological Weyl fermion semimetal state in MoxW1-xTe2.

The recent discovery of a Weyl semimetal in TaAs offers the first Weyl fermion observed in nature and dramatically broadens the classification of topological phases. However, in TaAs it has proven challenging to study the rich transport phenomena arising from emergent Weyl fermions. The series MoxW1−xTe2 are inversion-breaking, layered, tunable semimetals already under study as a promising platform for new electronics and recently proposed to host Type II, or strongly Lorentz-violating, Weyl fermions. Here we report the discovery of a Weyl semimetal in MoxW1−xTe2 at x=25%. We use pump-probe angle-resolved photoemission spectroscopy (pump-probe ARPES) to directly observe a topological Fermi arc above the Fermi level, demonstrating a Weyl semimetal. The excellent agreement with calculation suggests that MoxW1−xTe2 is a Type II Weyl semimetal. We also find that certain Weyl points are at the Fermi level, making MoxW1−xTe2 a promising platform for transport and optics experiments on Weyl semimetals.

Studies of metal–ferroelectric–GaN structures

A GaN-based metal–insulator–semiconductor (MIS) structure has been fabricated by using ferroelectric Pb(Zr0.53Ti0.47)O3 instead of conventional oxides as insulator gate. Because of the polarization field provided by ferroelectric and the high dielectric constant of ferroelectric insulator, the capacitance–voltage characteristics of GaN-based metal–ferroelectric–semiconductor (MFS) structures are markedly improved compared to those of other previously studied GaN MIS structures. The GaN active layer in MFS structures can reach inversion just under the bias of smaller than 5 V, which is the generally applied voltage used in semiconductor-based integrated circuits. The surface carrier concentration of the GaN layer in the MFS structure is decreased by one order compared with the background carrier concentration. The GaN MFS structures look promising for the practical application of GaN-based field effect transistors.

Nontrivial Berry phase and type-II Dirac transport in the layered material PdT e 2

Recently, the picture of type-II energy dispersion with broken Lorentz invariance has been adapted from Weyl to Dirac fermions. It is demonstrated in PdTe

Random telegraph signals and low-frequency noise in n-metal–oxide–semiconductor field-effect transistors with ultranarrow channels

{}_{2}

Simulation of electron storage in Ge/Si hetero-nanocrystal memory

in this paper by extensive evidence from electrical transport, de Haas--van Alphen oscillations, first-principles calculations, and angle-resolved photoemission spectroscopy. The type-II Dirac cone looks like a pinnacle in momentum space. It may be cut by the Fermi level with the result of a pair of Dirac pockets (of

Repairing atomic vacancies in single-layer MoSe 2 field-effect transistor and its defect dynamics

p

Sizeable Kane–Mele-like spin orbit coupling in graphene decorated with iridium clusters

/

Films with discrete nano-DLC-particles as the field emission cascade

n

Switching kinetics of interface states in deep submicrometre SOI n-MOSFETs

type), whose sizes change dramatically with the Fermi level. The nontrivial Berry phase of the hole pocket is also displayed. This also means a nonvanishing density of states in the whole Dirac cones, which makes PdTe

Band Structure Perfection and Superconductivity in Type-II Dirac Semimetal Ir1− x Pt x Te2

{}_{2}