We investigate the transport properties through magnetic superlattices with asymmetric double-barrier units in monolayer graphene.In N-periodic asymmetric double-barrier units,there is (N-1)-fold resonant peak splitting for transmission,but the splitting is (2N-1)-fold in N-periodic symmetric units.The transmission depends not only on the value of incident wavevectors but also on the value and the direction of transverse wavevectors.This renders the structure's efficient wavevector filters.In addition,the conductance of standard electrons with a parabolic energy spectrum is suppressed more strongly than that of Dirac electrons,whereas the resonances are more pronounced for Dirac electrons than for standard ones.
With the Coulomb gauge, the Chern-Simons-Georgi-Glashow (CSGG) model is quantized in the Dirac formalism for the constrained system. Combining the Gauss law and Coulomb gauge consistency condition, the difference between the Schwinger angular momentum and canonical angular momentum of the system is found to be an anomalous spin. The reason for this result lies in the fact that the Schwinger energy momentum tensor and the canonical one have different symmetry properties in the presence of the Chern-Simons term.
We investigate the dopant site selectivity of CaCu_(3)Ti_(4)O_(12)(CCTO)using the first principles calculations.Our results show that,for four cases of possible occupancy by La atom,lattice expansions and formation enthalpies with different dopant quantities indicate that doped La cations are preferentially substituted for Ca sites in CaCu_(3)Ti_(4)O_(12),which is excellent in agreement with the experimental observation(Choi et al.Adv.Mater.21(2009)885).Furthermore,more interesting information of doping is also explored by the analysis of density of states and it is found that La substituting for Cu may advance the electron conduction in CCTO.It supplies a potential solution for limitations of CCTO devices by exploring the effect when La substitutes for Cu sites in the CCTO crystal.
