The realization of quantum anomalous Hall effect in two dimensional electron gas.

The quantum anomalous Hall effect (QAHE), carrying dissipationless chiral edge states, occurs without any magnetic field. Two main strategies were proposed to host QAHE: the magnetic topological insulator thin films and graphene systems. Only the former one was realized in experiment at low temperature.

The electronic transport efficiency of a graphene charge carrier guider and an Aharanov-Bohm interferometer.

The electrostatic gating defined channel in graphene forms a charge carrier guider. We theoretically investigated electronic transport properties of a single channel and an Aharanov-Bohm (AB) interferometer, based on a charge carrier guider in a graphene nanoribbon. Quantized conductance is found in a single channel, and the guider shows high efficiency in the optical fiber regime, in good agreement with the experiment results.

Manipulation and Characterization of the Valley-Polarized Topological Kink States in Graphene-Based Interferometers.

Valley polarized topological kink states, existing broadly in the domain wall of hexagonal lattice systems, are identified in experiments. Unfortunately, only very limited physical properties are given. Using an Aharanov-Bohm interferometer composed of domain walls in graphene systems, we study the periodical modulation of a pure valley current in a large range by tuning the magnetic field or the Fermi level.

Magnetic field mediated conductance oscillation in graphene p-n junctions.

The electronic transport of graphene p-n junctions under perpendicular magnetic field is investigated in theory. Under low magnetic field, the transport is determined by the resonant tunneling of Landau levels and conductance versus magnetic field shows a Shubnikov-de Haas oscillation. At higher magnetic field, the p-n junction subjected to the quasi-classical regime and the formation of snake states results in periodical backscattering and transmission as magnetic field varies.

Investigation of valley-resolved transmission through gate defined graphene carrier guiders.

Massless charge carriers in gate potentials modulate graphene quantum well transport in the same way that a electromagnetic wave propagates in optical fibers. A recent experiment by Kim et al (2016 Nat. Phys.

The Andreev reflection of zero line mode in graphene-superconductor hybrid junction.

The zero line mode (ZLM) in two dimensional materials provides a quasi-one dimensional path for electronic transport. We report the theoretical investigation of the Andreev reflection of ZLM by using the staggered graphene-superconductor based models. For a two-terminal system in which the valley index is well preserved, when graphene is zigzag edged, the Andreev reflection coefficient can be either large or strongly suppressed depending on the symmetric properties of the transverse wave function in graphene ribbon.

Electronic transport between quantum Hall states and quantum anomalous Hall states in a graphene nanoribbon based heterojunction.

We theoretically investigate the electronic transport between quantum Hall states and quantum anomalous Hall states in a zigzag edged graphene nanoribbon based two-terminal heterojunction. The electrical conductance of the system is calculated by the method of the non-equilibrium Green's function and Landauer-Büttiker formula. We find perfect transmission through the junction when the propagation direction of the charge carriers is the same at the same edge in both regions.

Spin thermopower and thermoconductance in a ferromagnetic graphene nanoribbon.

The spin thermoelectric properties of a zigzag edged ferromagnetic (FM) graphene nanoribbon are studied theoretically by using the non-equilibrium Green's function method combined with the Landauer-Büttiker formula. By applying a temperature gradient along the ribbon, under closed boundary conditions, there is a spin voltage ΔV(s) inside the terminal as the response to the temperature difference ΔT between two terminals. Meanwhile, the heat current ΔQ is accompanied from the 'hot' terminal to the 'cold' terminal.

Transport properties of monolayer and bilayer graphene p-n junctions with charge puddles in the quantum Hall regime.

Recent experiments have confirmed that the electron-hole inhomogeneity in graphene is a new type of charge disorder. Motivated by such confirmation, we theoretically study the transport properties of a monolayer graphene (MLG) based p-n junction and a bilayer graphene (BLG) p-n junction in the quantum Hall regime where electron-hole puddles are considered. By using the non-equilibrium Green function method, both the current and conductance are obtained.

Electronic transport through a graphene-based ferromagnetic/normal/ferromagnetic junction.

Electronic transport in a graphene-based ferromagnetic/normal/ferromagnetic junction is investigated by means of the Landauer-Büttiker formalism and the nonequilibrium Green function technique. For the zigzag edge case, the results show that the conductance is always larger than e(2)/h for the parallel configuration of lead magnetizations, but for the antiparallel configuration the conductance becomes zero because of the band-selective rule. Therefore, a magnetoresistance (MR) plateau emerges with the value 100% when the Fermi energy is located around the Dirac point.

Controllable Andreev retroreflection and specular Andreev reflection in a four-terminal graphene-superconductor hybrid system.

We report the investigation of electron transport through a four-terminal graphene-superconductor hybrid system. Because of the quantum interference of the reflected holes from two graphene-superconductor interfaces with a phase difference theta, it is found that the specular Andreev reflection vanishes at theta=0 while the Andreev retroreflection disappears at theta=pi. This means that retroreflection and specular reflection can be easily controlled and separated in this device.