Complex Landau levels and related transport properties in the strained zigzag graphene nanoribbons

TL;DR

This paper explores how strain-induced pseudo magnetic fields in graphene nanoribbons create complex Landau levels, affecting transport properties and enabling tunable valley-polarized currents for potential valleytronics applications.

Contribution

It introduces the concept of effective orbital magnetic fields combining real and pseudo magnetic fields, providing a new framework to analyze complex Landau levels in strained graphene.

Findings

Pseudo Landau levels are fragile against disorders and dephasing.

Tuning real magnetic fields and Fermi energy enhances robustness.

Valley-polarized currents can be effectively controlled.

Abstract

The real magnetic fields (MFs) acting on the graphene can induce flat real Landau levels (LLs). As an analogy, strains in graphene can produce significant pseudo MFs, triggering the appearance of dispersive pseudo LLs. By analyzing the low-energy effective Hamiltonian, we introduce the concept of the effective orbital MFs to integrate the real MFs and pseudo MFs. Accordingly, we obtain the complex LLs which incorporate the real LLs and pseudo LLs, and calculate the related transport properties. These concepts enable us to uncover the mechanisms driving the fragility of pseudo LLs against disorders and dephasing, proving that tuning the real MFs and Fermi energy can effectively improve the robust performances. Furthermore, the tunability of the valley-polarized currents is also studied, opening up new possibilities for the design of valleytronics devices.