Quantum correlations in the frustrated XY model on the honeycomb lattice.

We have investigated the spin-1/2 XY frustrated antiferromagnetic Heisenberg honeycomb model, which features an intermediate region in its ground state phase diagram that is not well understood. The two dominant phases in the diagram are the quantum spin-liquid (QSL) and the antiferromagnetic Ising order. Quantum correlations suggest that the QSL phase is likely to exhibit entanglement.

Entanglement and quantum correlations in the XX spin-1/2 honeycomb lattice.

The ground state phase diagram of the dimerized spin-1/2 XX honeycomb model in presence of a transverse magnetic field (TF) is known. With the absence of the magnetic field, two quantum phases, namely, the Néel and the dimerized phases have been identified. Moreover, canted Néel and the paramagnetic (PM) phases also emerge by applying the magnetic field.

Thermoelectric efficiency in three-terminal graphene nano-junctions.

The thermoelectric efficiency of a thermal machine consisting of a triangular graphene nano-junction connected to three electrodes in the linear response regime is studied. Using the Onsager formalism and a combination of semi-empirical tight-binding calculations as well as Green's function theory, the efficiency at maximum output power which can be written in terms of generalized figures of merit is investigated. The results for a set temperature and chemical potential parameters have shown that adding a third terminal improves the efficiency at maximum output power compared to the two-terminal setup.

Shot Noise of Charge and Spin Current of a Quantum Dot Coupled to Semiconductor Electrodes.

On the basis of the scattering matrix theory and nonequilibrium green function method, we have investigated the fluctuations of charge and spin current of the systems that consist of a quantum dot (QD) with a resonant level coupled to two semiconductor contacts within in alternative site (AS) and alternative bond (AB) framework, where two transverse (Bx) and longitudinal (Bz) magnetic fields are applied to the QD. It is only necessary to use the autocorrelation function to characterize the fluctuations of charge current for a twoterminal system because of the relation that is defined as Σα e Sαβ = Σβ e Sαβ = 0. Our result shows that both auto-shot noise (SLL) and cross-shot noise (SLR) are essential to characterize the fluctuations of spin current when Bx is present.