Magnetic Nanostructure for Zigzag Graphene Nanoribbons and Application in Nano Electronics

Abstract

We have studied graphene zigzag edge terminated nanostructures for the magnetic phase diagram considering mean field analysis. In this case four fermion interaction was treated in the magnetic channel. The quantum fluctuations were not captured at the mean field. We have made variational Monte Carlo calculations of the ground state. It was found that the ground state at zero doping was the antiferromagnetic configuration. The edge moment was found smaller than the mean field value due to quantum fluctuations both the antiferromagnetism and ferromagnetism edge moments were stable and they remained unchanged upon increasing the length of the ribbon producing the magnetism robust. The possible chemical modification of graphene nanoribbons to produce and internal doping to engendered the magnetic transition. A ferromagnetic structure of a zigzag edge terminated nanoribbon with boron atom substituted in place of carbons while undoped nanoribbons had a antiferromagnetic configuration within the same calculation. It was found that a Weber Fechner response of nanoribbons played a central role in determining their magnetism. We have formulated a effective theory which leaded to a magnetic phase diagram of lightly doped nanoribbons including analytical expressions for the width dependence of magnetization, excitation gap and the critical doping needed to engender magnetic transitions. The results found were in good agreement with previously obtained results.