It depends on the meaning of spiritual.
In the sense of spirituality meaning "Not driven by material goals" atheists can be spiritual. They can do altruistic work for low pay, work for the betterment of the poor, do art and music for its own sake.
In the sense of "spirituality" meaning to be aware of a soul or spirit, or aware of and compliant to religious values, or aware of forces beyond the physical world e.g. the supernatural - no they are not spiritual. It goes with the world view they espouse - This is all there is.
An atheist does not believe in a higher power. People believe in spiritual practices while not prescribing to ethereal spirits. People manipulate subtle energies without recognition of an external force.