  Electric control of spins has been a longstanding goal in the field of solid
state physics due to the potential for increased efficiency in information
processing. This efficiency can be optimized by transferring spintronics to the
atomic scale. We present electric control of spin resonance transitions in
single molecules by employing electron spin resonance scanning tunneling
microscopy (ESR-STM). We find strong bias voltage dependent shifts in the ESR
signal of about ten times its linewidth, which is due to the electric field
induced displacement of the spin system in the tunnel junction. This opens up
new avenues for ultrafast control of coupled spin systems, even towards atomic
scale quantum computing, and expands on understanding and optimizing spin
electric coupling in bulk materials.
