Spin dynamics and relaxation in graphene nanoribbons: electron spin resonance probing.
Here we report the results of a multifrequency (~9, 20, 34, 239.2, and 336 GHz) variable-temperature continuous wave (cw) and X-band (~9 GHz) pulse electron spin resonance (ESR) measurement performed at cryogenic temperatures on potassium split graphene nanoribbons (GNRs). Important experimental findings include the following: (a) The multifrequency cw ESR data infer the presence of only carbon-related paramagnetic nonbonding states, at any measured temperature, with the g value independent of microwave frequency and temperature. (b) A linear broadening of the ESR signal as a function of microwave frequency is noticed. The observed linear frequency dependence of ESR signal width points to a distribution of g factors causing the non-Lorentzian line shape, and the g broadening contribution is found to be very small. (c) The ESR process is found to be characterized by slow and fast components, whose temperature dependences could be well described by a tunneling level state model. This work not only could help in advancing the present fundamental understanding on the edge spin (or magnetic)-based properties of GNRs but also pave the way to GNR-based spin devices.
INPAC, Institute for Nanoscale Physics and Chemistry, Semiconductor Physics Laboratory, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium. ssingam@ncsu.edu
Singamaneni S
SS
Rao
Andre
A
Stesmans
Johan
J
van Tol
Dmitry V
DV
Kosynkin
A
A
Higginbotham-Duque
Wei
W
Lu
Alexander
A
Sinitskii
James M
JM
Tour
D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D006108:Graphite / Q000737:chemistry*; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013113:Spin Labels
D013113:Spin Labels; D006108:Graphite