  The electrical manipulation of magnetization by current-induced spin torques
has given access to realize a plethora of ultralow power and fast spintronic
devices such as non-volatile magnetic memories, spin-torque nano-oscillators,
and neuromorphic computing devices. Recent advances have led to the notion that
relativistic spin-orbit coupling is an efficient source for current-induced
torques, opening the field of spin-orbitronics. Despite the significant
progress, however, the fundamental mechanism of magnetization manipulation, the
requirement of spin currents in generating current-induced torques, has
remained unchanged. Here, we demonstrate the generation of current-induced
torques without the use of spin currents. By measuring the current-induced
torque for naturally-oxidized-Cu/ferromagnetic-metal bilayers, we observed an
exceptionally high effective spin Hall conductivity at low temperatures despite
the absence of strong spin-orbit coupling. Furthermore, we found that the
direction of the torque depends on the choice of the ferromagnetic layer, which
counters the conventional understanding of the current-induced torque. These
unconventional features are best interpreted in terms of an orbital counterpart
of the spin torque, an orbital torque, which arises from the orbital Rashba
effect and orbital current. These findings will shed light on the underlying
physics of current-induced magnetization manipulation, potentially altering the
landscape of spin-orbitronics.
