Intercalated europium metal in epitaxial graphene on SiC

X-ray magnetic circular dichroism (XMCD) reveals the magnetic properties of intercalated europium metal under graphene on SiC(0001). The intercalation of Eu nanoclusters (average size 2.5 nm) between graphene and SiC substate are formed by deposition of Eu on epitaxially grown graphene that is subsequently annealed at various temperatures while keeping the integrity of the graphene layer. Using sum-rules analysis of the XMCD of Eu M4,5 edges at T=15 K, our samples show paramagnetic-like behavior with distinct anomaly at T≈90 K, which may be related to the Nèel transition, TN=91 K, of bulk metal Eu. We find no evidence of ferromagnetism due to EuO or antiferromagnetism due to Eu2O3, indicating that the graphene layer protects the intercalated metallic Eu against oxidation over months of exposure to atmospheric environment. Disciplines Materials Science and Engineering | Metallurgy This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/ameslab_manuscripts/84 PHYSICAL REVIEW MATERIALS 1, 054005 (2017) Intercalated europium metal in epitaxial graphene on SiC Nathaniel A. Anderson,1 Myron Hupalo,1 David Keavney,2 Michael C. Tringides,1 and David Vaknin1,* 1Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA 2X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA (Received 8 August 2017; revised manuscript received 27 September 2017; published 25 October 2017) X-ray magnetic circular dichroism (XMCD) reveals the magnetic properties of intercalated europium metal under graphene on SiC(0001). The intercalation of Eu nanoclusters (average size 2.5 nm) between graphene and SiC substate are formed by deposition of Eu on epitaxially grown graphene that is subsequently annealed at various temperatures while keeping the integrity of the graphene layer. Using sum-rules analysis of the XMCD of Eu M4,5 edges at T = 15 K, our samples show paramagnetic-like behavior with distinct anomaly at T ≈ 90 K, which may be related to the Nèel transition, TN = 91 K, of bulk metal Eu. We find no evidence of ferromagnetism due to EuO or antiferromagnetism due to Eu2O3, indicating that the graphene layer protects the intercalated metallic Eu against oxidation over months of exposure to atmospheric environment. DOI: 10.1103/PhysRevMaterials.1.054005