Self-similar transport, spin polarization and thermoelectricity in complex silicene structures

Abstract

2D materials open the possibility to study Dirac electrons in complex self-similar geometries. The two-dimensional nature of materials like graphene, silicene, phosphorene and transition-metal dichalcogenides allow the nanostructuration of complex geometries through metallic electrodes, interacting substrates, strain, etc. So far, the only 2D material that presents physical properties that directly reflect the characteristics of the complex geometries is monolayer graphene. In the present work, we show that silicene nanostructured in complex fashion also displays self-similar characteristics in physical properties. In particular, we find self-similar patterns in the conductance, spin polarization and thermoelectricity of Cantor-like silicene structures. These complex structures are generated by modulating electrostatically the silicene local bandgap in Cantor-like fashion along the structure. The charge carriers are described quantum relativistically by means of a Dirac-like Hamiltonian. The transfer matrix method, the Landauer–Büttiker formalism and the Cutler–Mott formula are used to obtain the transmission, transport and thermoelectric properties. We numerically derive scaling rules that connect appropriately the self-similar conductance, spin polarization and Seebeck coefficient patterns. The scaling rules are related to the structural parameters that define the Cantor-like structure such as the generation and length of the system as well as the height of the potential barriers. As far as we know this is the first time that a 2D material beyond monolayer graphene shows self-similar quantum transport as well as that transport related properties like spin polarization and thermoelectricity manifest self-similarity.

Quantum transport in novel self-similar structure based on graphene

“…In the case of conductance, it shows an oscillatory behaviour that can be directly described by bound states [33]. Similarly, self-similar patterns in silicene were studied, and it was reported that scaling rules in conductance and thermoelectric effects between generations of silicene structures [34].…”

Thermoelectric effects in selfsimilar multibarrier structure based on monolayer graphene

“…According to several studies, environmentally wasted heat represents more than 50% of the energy produced 27 . Numerous theoretical studies have been carried out on the thermoelectric effect in various systems based on 2D materials, showing an improvement in the thermoelectric performance 28,29 .…”

Electron scattering in silicene quantum dot with a time-periodic potential

“…This characteristic makes silicene useful in the spintronic applications and semiconductor industry, such as room temperature field-effect transistor (FET) [5]. In recent years, many studies have been focused on the transport properties in silicene structures [6][7][8][9][10][11][12][13][14]. Kharadi et al [11] demonstrated that due to the generation of band gap in silicene via hydrogenation of silicene, the spin-filtering efficiency reaches up to 96%.…”