Related Experiment Video
Updated: Sep 19, 2025

Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
Spin Polarization and Transport Properties of Flat Bands in Covalently Functionalized Graphene-Based Junctions
Hui-Qing Zhang1, Han Ma1, Guang-Ping Zhang1
1Shandong Key Laboratory of Medical Physics and Image Processing & Shandong Provincial Engineering and Technical Center of Light Manipulations, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
Abstract:
Spin transport properties contributed by the flat bands have become a fascinating issue in device physics. Based on the first-principles method, we investigate the spin polarization and transport properties of covalently functionalized graphene sandwiched between two nonmagnetic electrodes with different contact sites. The analysis of electronic states demonstrates that the two spin-split flat bands originating from covalently functionalized graphene are severely perturbed when the horizontal distance between the Cu tip electrode and the functionalized C atom is less than the length of the C-C bond. The two flat bands degrade into partially polarized midgap states in the case of strong interactions between the Cu tip electrode and functionalized graphene. Spin-dependent transport calculations show that the flat bands may serve efficient transmission in all cases, while a large spin polarization of current of about 90% is achieved when the flat bands are weakly disturbed and a spin-split band gap is preserved. This work reveals the conditions for spin-split flat bands in covalently functionalized graphene in the situation of junctions and their potential prospects in spin-polarized transport in spintronic devices.
Related Concept Videos
Biasing of Metal-Semiconductor Junctions
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
Band Theory
The energy difference between these bands is known as the band gap.
Conductor, Semiconductor,...
Metal-Semiconductor Junctions
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The...
Spin–Spin Coupling: One-Bond Coupling
Semiconductors
Metals such as copper (Cu), zinc (Zn), or lead (Pb) have low resistivity and feature conduction bands that are either not fully occupied or overlap with the valence band, making a bandgap non-existent. This allows electrons in the highest energy levels of the valence band to easily transition to the conduction band upon gaining...
Ferromagnetism

