Doping Graphene with Substitutional Mn.

Pin-Cheng Lin,Hans Hofsäss,Steven Brems,Maya N Nair,Ken Verguts,Lino M C Pereira,Giovanni Di Santo,Stefan De Gendt,Harsh Bana,Manuel Auge,Guido Fratesi,Steven De Feyter,Antonio Tejeda,Renan Villarreal,Simona Achilli,Luca Petaccia

doi:10.1021/acsnano.1c00139

Abstract

We report the incorporation of substitutional Mn atoms in high-quality, epitaxial graphene on Cu(111), using ultralow-energy ion implantation. We characterize in detail the atomic structure of substitutional Mn in a single carbon vacancy and quantify its concentration. In particular, we are able to determine the position of substitutional Mn atoms with respect to the Moiré superstructure (i.e., local graphene-Cu stacking symmetry) and to the carbon sublattice; in the out-of-plane direction, substitutional Mn atoms are found to be slightly displaced toward the Cu surface, that is, effectively underneath the graphene layer. Regarding electronic properties, we show that graphene doped with substitutional Mn to a concentration of the order of 0.04%, with negligible structural disorder (other than the Mn substitution), retains the Dirac-like band structure of pristine graphene on Cu(111), making it an ideal system in which to study the interplay between local magnetic moments and Dirac electrons. Our work also establishes that ultralow-energy ion implantation is suited for substitutional magnetic doping of graphene. Given the flexibility, reproducibility, and scalability inherent to ion implantation, our work creates numerous opportunities for research on magnetic functionalization of graphene and other two-dimensional materials.

Highlights

Magnetic functionalization of graphene is being intensively investigated for its fundamental appeal as well as for applications in next-generation electronics.[1,2,3,4,5,6,7,8] The formation of local magnetic moments and their interactions in graphene, which is intrinsically diamagnetic and exhibits electronic behavior beyond that of conventional metals and semiconductors, remains poorly understood
Using angle-resolved photoemission spectroscopy (ARPES), we show that graphene doped with substitutional metal dopant (Mn) retains the Dirac-like behavior of pristine graphene
This article focuses on the 700 ◦C annealed state, where scanning tunneling microscopy (STM) measurements provide the clearest identification of Mn defects that, according to the analysis described in the following paragraph, we identify as substitutional Mn atoms in graphene

Summary

Introduction

Magnetic functionalization of graphene is being intensively investigated for its fundamental appeal as well as for applications in next-generation electronics.[1,2,3,4,5,6,7,8] The formation of local magnetic moments and their interactions in graphene, which is intrinsically diamagnetic and exhibits electronic behavior beyond that of conventional metals and semiconductors, remains poorly understood. Substitutional doping with transition elements[11,12,18] has been achieved using non-equilibrium conditions: first, vacancies are formed by bombardment with electrons or ions, and subsequently the magnetic dopant atoms are deposited, filling the vacancies that have not dynamically annealed between the two steps Such dual-step processes are difficult to control, especially given the complex dynamics of vacancies in graphene, strongly limiting their reliability, reproducibility and scalability. Using angle-resolved photoemission spectroscopy (ARPES), we show that graphene doped with substitutional Mn retains the Dirac-like behavior of pristine graphene These findings motivate further research on magnetic functionalization of 2D materials, strongly benefiting from the high stability of substitutional doping, together with the high degree of control, flexibility and scalability of ultra-low energy ion implantation

Methods

Results

Conclusion