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Abstract: The stable boron carbon nanotube superlattices (BCNTSLs) that are constructed by periodically connecting carbon nanotube (CNT) and boron nanotube (BNT) with different lengths and diameters are predicted by employing the density functional first-principles calculations. The geometrical and electronic structures as well as quantum conductance of BCNTSLs are studied. It is found that the superlattices can be metallic or semiconducting depending on tube diameters and the ratio of BNT to CNT segments in a periodic unit. The confined states in the superlattice are observed. The present study could offer a useful way for designing some functional nanodevices. [Copyright &y& Elsevier]

Abstract: The magnetic behaviors of a spin-1/2 alternating Heisenberg antiferromagnetic chain in a staggered transverse magnetic field is studied by means of the density-matrix renormalization group method and Jordan–Wigner transformation. Quantum phase transitions of different types are observed in the Néel and XY-like gapless phases, which result from the competitions between the staggered transverse field and magnetic orders induced by anisotropy and alternating interactions. The results are compared with the mean-field and some exactly resolved results. [Copyright &y& Elsevier]