Transport properties through graphene-based fractal and periodic magnetic barriers

Abstract

We investigate the transmission of electrons in a single layer graphene system subjected to nanoscale magnetic barriers and wells arranged in the Cantor pre-fractal and the finite periodic distribution. We find that the angular threshold and angular asymmetry of the transmission spectra are closely related to the ratio between the magnitude of the vector potential and the incident energy (|A|/E), which also determine the number and width of the resonant domains for the finite periodically magnetic modulation and the splitting features for the pre-fractal distribution. For the finite periodically magnetic modulation, the position, magnitude, and interval of the oscillatory domains in the conductance spectra are determined by the value |A|. However, due to the disorder of the pre-fractal distribution, the oscillation of the conductance spectrum is less regular compared to the corresponding one of the finite periodic distribution. We also find that the conductance approaches the classical limit in the high-Fermi-energy region but exceeds it in the low-Fermi-energy region, and the critical point of the two regions is negatively correlated with the magnitude of the vector potential.

Spin Transport in Fractal Conductors With the Rashba Spin-Orbit Coupling

“…13,14 However, experimentally, most observations so far have been attributed to the extrinsic SHE. 9À11 Some recent observation of the nonlocal SHE was also found in various systems, 5,11,15 including graphene 6,16,17 which can only be explained by the intrinsic mechanism. 18 Considerable e®ort in this direction has already revealed the unique features of spin-polarized electron transport in the so-called two-terminal nano-or mesoscopic devices.…”

“…1 Spin separation in semiconductors is not only possible, but also quite natural, so that manipulating spin properties of charge carriers in electronics is a promising¯eld of research. 2À4 Recently, di®erent types of SHE were reported for di®erent geometrical setups of both magnetic 5,6 and nonmagnetic materials. 7,8 Local SHE often attributed both as extrinsic SHE, 9À11 and intrinsic SHE.…”

Self-similar conductance patterns in graphene Cantor-like structures

“…Within this context, self-similarity in aperiodic structures in graphene is not the exception. Several works claim that the transmission probability sustains self-similar characteristics in Fibonacci and Thue-Morse superlattices 15–18 , but once again the scale factors that connect the transmission patterns are not derived. Recently, we have shown that the transmission properties of graphene subjected to self-similar and self-affine multi-barrier structures present self-similar characteristics 19–21 .…”

Fibonacci quasiregular graphene-based superlattices: Quasiperiodicity and its effects on the transmission, transport and electronic structure properties

“…So, by considering the importance of the quasi-periodic modulation, from both the fundamental and technological standpoints, it seems natural that it be an extension for any novel material. To this respect graphene is not the exception, and in the last years the interest in aperiodic or quasi-periodic modulation in graphene is rising [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. All these studies focus primarily on monolayer graphene, and the preferred mechanism to create the quasi-periodic pattern has been the electrostatic field effect.…”

“…All these studies focus primarily on monolayer graphene, and the preferred mechanism to create the quasi-periodic pattern has been the electrostatic field effect. So far, the quasi-periodic patterns studied in graphene have been Cantor [33][34][35], Fibonacci [36][37][38][39][40], Thue-Morse [41][42][43][44][45][46][47], Double-Period [48] and Gaussian [49,50]. One of the most remarkable characteristics of quasi-periodic patterns in graphene, regardless of the quasi-periodic sequence used, is a zero-gap associated to an unusual Dirac point.…”