  The aim of voltage control of magnetism is to reduce the power consumption of
spintronic devices. For a spin valve, the magnetization directions of two
ferromagnetic layers determine the giant magnetoresistance magnitude. However,
achieving all-voltage manipulation of the magnetization directions between
parallel and antiparallel states is a significant challenge. Here, we
demonstrate that by utilizing two exchange-biased Co/IrMn bilayers with
opposite pinning directions and with ferromagnetic coupling through the
Ruderman-Kittel-Kasuya-Yosida interaction between two Co layers, the
magnetization directions of the two ferromagnetic layers of a spin valve can be
switched between parallel and antiparallel states through allvoltage-induced
strain control. The all-voltage controlled giant magnetoresistance is
repeatable and nonvolatile. The rotation of magnetizations in the two Co layers
under voltages, from antiparallel to parallel states, occurs in opposite
directions as revealed through simulations utilizing the
Landau-Lifshitz-Gilbert equation. This work can provide valuable reference for
the development of low-power all-voltage-controlled spintronic devices.
