Transport and non-equilibrium properties of graphene and high-temperature superconductors.

摘要

This dissertation focuses on the transport aspect of graphene nanoribbons and high-transition temperature superconductors (HTSC). Concerning graphene, we propose a nano Peltier cooling device using a single graphene nanoribbon. Based on the membrane-like features of graphene, its cooling power can be tuned after fabrication by applying uniaxial pressure. We estimate the cooling power using two different methods and find that it is close to that achievable with the best cooling devices. In HTSC, we study the transport noise and vortex dynamics in the pseudogap regime. The equilibrium noise power spectrum of the magnetization in two-dimensional Random Field Ising Model (2D RFIM) is studied such that a crossover temperature is identified. Spin configurations in 2D RFIM are further mapped into resistance networks to study the behavior of transport noise in the local nematic phase. Our results are qualitatively consistent with recent observations in YBCO experiments. Vortex dynamics in extremely type II superconductor is studied using modified Coulomb gas model. Nernst signals and diamagnetism in the vortex smectic phase is estimated. Our results serve as a probe for experimentally detecting the vortex smectic phase, which is theoretically predicted in 2003 by Carlson, et al.