Roller Coaster in a Flatland: Magnetoresistivity in Eu-Intercalated Graphite

Novel phenomena in magnetically-intercalated graphite has been a subject of much research, pioneered and promoted by M.~S. G.~Dresselhaus many others the 1980s. Among most enigmatic findings that era was dramatic, roller-coaster-like behavior magnetoresistivity EuC$_6$ compound, which magnetic Eu$^{2+}$ ions form triangular lattice is commensurate to honeycomb planes. In this study, we provide long-awaited {\it microscopic} explanation behavior, demonstrating resistivity dominated spin excitations Eu-planes their highly nontrivial evolution with field. Together our theoretical analysis, present study showcases power synthetic 2D materials as source potentially significant insights into nature exotic excitations.