Edge magnetism and electronic properties in novel two dimensional materials: graphene and phosphorene

26/04/2018 @ 11:00 AM – 12:30 PM Asia/Singapore Timezone
S16 Level 6 – Theory Common Conference Room

Speaker: Yang Guang (杨光)
Affiliation: Beijing Normal University
Host: Associate Professor Shaffique Adam
Location: Click HERE for directions

Abstract Details: Recently, two dimensional materials like graphene and phosphorene have been attracting great attention for its possible application in new electronics. My doctoral work focus on the tailoring magnetic and electronic properties of graphene, phosphorene and the single-layer form of phosphorene allotropes.

By means of two different large scale quantum Monte-Carlo methods, we propose that relatively weak interactions can lead to remarkable edge magnetism in the phosphorene nanoribbons. The ground state constrained path quantum Monte-Carlo simulations reveal strong ferromagnetic correlations along the zigzag edges, and the finite temperature determinant quantum Monte-Carlo calculations show a high Curie temperature up to room temperature. We argue that the change of the topological structure that induced by the natural strong anisotropy in phosphorene is the key to understand the enhancement of the edge ferromagnetism compared with that of the isotropic case, namely graphene. Thus the strain-tuning of edge magnetism in zigzag graphene nanoribbons is also proposed.

Most recently, another stable monolayer of a new phosphorus allotrope with a direct gap, called green phosphorene, has been predicated. Using the first principle density functional theory calculations, we find that it can sustain a tensile strain limit in the armchair direction up to 35% and reveal the nature of its more puckered structure. Moreover, the direct-indirect band gap transition happens under appropriate strain. These works may open up to new possibilities of engineering further electronic and spintronic devices.

About the Speaker: I am a doctoral student from Beijing Normal University under the direction of Prof. Tianxing Ma in condensed matter physics. During my doctoral period, I have worked on tailoring the magnetic properties of 2D materials, especially graphene and phosphorene using quantum Monte Carlo simulations. Last year, I got an opportunity to cooperate with Prof. Xihong Peng as a short-term visitor at Arizona State University. During that time, I did some research on tuning the electronic properties of green phosphorene using the first principle density functional theory calculations.