Size Effect Of RKKY Interaction In Nanoribbon

The study of mesoscopic nano-scale system has become one of the frontier areas in condensed matter physics in recent years. As the study goes further, a serial of intrinsic information related to the systems constantly emerges and thus a promising future with applications has been developed. The RKKY interaction of local spins in a nano system has received generous attention for its mechanism may enable a physical entity to carry and help transport quantum information.In this thesis, we study the RKKY interaction between two local spins in a nano-ribbon system. Using the method of second-quantization, the mathematical expression of the RKKY interaction in our system is given. After the numerical calculation, we conclude that the intensity of the RKKY interaction in our system closely depends on three factors: the width of the nano-ribbon, the lateral and longitudinal separating distance between the local spins, respectively.Our research provides a theoretical basis for control of the RKKY interactions of local spins in nano-ribbons. Moreover, for designing and realizing quantum-devices with good characteristics, our work provides a valuable physics model and theory supports.We summarized the definition and characteristic of the mesoscopic system at the beginning of this thesis. By using the eigenfunction of the single-particle Hamiltonian as basis of second quantization, We derived the analytic expression of RKKY interaction in the quansi one dimensional electrons system and find the relation between interaction intensity and the limited width ,electron density ,location of the magnetic impurity atoms as follows.All curves amplitude have showen trend of shock and reduced. If larger ofΔr ,the smaller of amplitude. The graphics Period were affected by the density of conduct electronsρ,the bigger ofρ,the smaller of period. The last effect is so-called size effect, in other words, which expressed the dependency relationship between intensity I and limited width of d, we have step-down amplitude and increscent period with width d.Our results clearly indicated that the RKKY interaction can be significantly modified by a limited width of the quasi one dimensional nanostructure system.