  Manipulation of antiferromagnetic (AFM) spins by electrical means is on great
demand to develop the AFM spintronics with low power consumption. In spite of
the electrical modulation of insulated AFMs through coupling between their
intrinsic ferroelectricity and antiferromagnetism, direct electrical control of
AFM metals remains challenging due to the screening effect by the surface
charge, and the manipulation is confined to a limited depth of atomic
dimensions, which is insufficient to form a stable AFM exchange spring. In the
present letter we primarily report a reversible electrical control of exchange
spring in AFM metals, using an ionic liquid to exert a substantial
electric-field effect. The exchange spring could transfer the force to the
ferromagnet/antiferromagnet interface, enabling a deeper modulation depth in
AFM metals. The manipulation of AFM moments by gate voltage is demonstrated in
[Co/Pt]/IrMn model system and a single IrMn layer with the IrMn thickness up to
5 nm. Besides the fundamental significance of modulating the spin structures in
metallic AFM via all-electrical fashion, the present finding would advance the
development of low-power-consumption AFM spintronics.
