Abstract
Modifying the properties of graphene has gained wide interest for a plethora of potential applications, including spintronics. One approach has demonstrated that proton irradiation can induce ferromagnetism in graphene as well as in graphite. However, little is known about how the protons interact with graphene, the mechanism that creates the ferromagnetism, or whether the protons remain in the graphene. Here we report an investigation, broadly relevant to graphitic carbon, using low-energy (360–2000 eV) ions of hydrogen, deuterium, and helium implanted into multilayer epitaxial graphene. Complementary x-ray and neutron reflectivity demonstrate that essentially all of the implanted hydrogen remains chemisorbed in graphene. In situ x-ray diffraction reveals significantly different rates of interlayer expansion of the multilayer graphene. Analysis of these data demonstrates that the interlayer expansion arises entirely from the interstitials created by the ions and not from hydrogen that remains in the graphene. The results also establish a quantitative measure of the layer expansion due to carbon interstitials. Magnetometry and x-ray diffraction studies show that the magnetic moment relates to the amount of interstitial carbon rather than the amount of hydrogen, demonstrating that the induced room-temperature ferromagnetism arises directly from the disrupted bonding of the carbon lattice.
| Original language | English |
|---|---|
| Pages (from-to) | 462-472 |
| Number of pages | 11 |
| Journal | Carbon |
| Volume | 192 |
| DOIs | |
| State | Published - Jun 15 2022 |
Funding
The authors would like to acknowledge the support of the National Science Foundation grant no. DGE-1069091 as well as support from the Oak Ridge National Laboratory GO! Fellowship. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education for the DOE under contract number DE-SC0014664. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. A portion of this work was supported by the University of Missouri Electron Microscopy Core Excellence in Electron Microscopy award. A portion of the ion irradiation work was supported by the Department of Energy (DOE), Office of Science , Basic Energy Sciences , Materials Sciences and Engineering Division. A portion of this research was conducted at the Center for Nanophase Materials Sciences, which is a Department of Energy Office of Science User Facility.