FMR evidence of ferromagnetic correlations at zigzag edge states in single-layer graphene

•Magnetism of zigzag edges of single layer graphene can be studied by FMR/ESR method.•Ferromagnetic spin correlation lengths were evidenced.•Magnetic order in low-dimensional systems is sensitive to thermal fluctuations.•ESR spectra of conduction electrons show Pauli type behavior.

Magnetic properties of zigzag edges of single-layer graphene were investigated by ferromagnetic resonance (FMR)/electron spin resonance (ESR) technique. We observed the FMR lines in single-layer graphene, which provide the most direct experimental proof of the theoretical prediction of ferromagnetic correlations at zigzag edges. To explain the observed temperature dependence of the FMR lines we analyzed the magnetic spin correlation length, which is responsible for magnetic ordering in these quasi-1D ferromagnetic nanodomains formed by zigzag edges. ESR spectra of conduction electrons were also studied.