  Electronic carriers in graphene show a high carrier mobility at room
temperature. Thus, this system is widely viewed as a potential future
charge-based high-speed electronic-material to complement- or replace- silicon.
At the same time, the spin properties of graphene have suggested improved
capability for spin-based electronics or spintronics, and spin-based quantum
computing. As a result, the detection, characterization, and transport of spin
have become topics of interest in graphene. Here we report a microwave
photo-excited transport study of monolayer and trilayer graphene that reveals
an unexpectedly strong microwave-induced electrical-response and dual
microwave-induced resonances in the dc-resistance. The results suggest the
resistive detection of spin resonance, and provide a measurement of the
g-factor, the spin relaxation time, and the sub-lattice degeneracy-splitting at
zero-magnetic-field.
