Ferromagnetic Proximity Induced Coupling and Exchange Splitting Effects in Graphene*

Ferromagnet (FM)/2D material interface with broken symmetry is a potential avenue for new physics and to realize exchange field controllable future spintronics devices. Proximity-induced effects of a FM on TI and graphene (G) have been explored previously with EuS as the ferromagnet, inducing magnetic correlations in the adjacent layer [1]. Magnetic semiconductor GdN would enable higher temperature operation. We report successful sputter growth of ultrathin excellent GdN films on high-quality G synthesized on SiC substrate to form G/FM heterostructures. The properties of G are unperturbed with 15 nm thick GdN film grown over it, having a magnetic moment ≈ 7 μB and Curie temperature ≈ 33 K. Temperature-dependent Raman spectrum of electric field tunable GdN/G system shows a clear signature of graphene G peak near 1580 cm-1 and G’ peak near 2700 cm-1 confirming its quality. The induced magnetic correlations in G creating exchange gap in the Dirac surface states by GdN is investigated. Furthermore, patterning a superconductor over this bilayer for Josephson pair tunnelling studies in G will be presented.

[1] P Wei et al, PRL 110, 186807 (2013); Nat. Mat. 15, 711 (2016); Katmis et al Nature 533, 513 (2016)