  Antiferromagnets have been generating intense interest in the spintronics
community, owing to their intrinsic appealing properties like zero stray field
and ultrafast spin dynamics. While the control of antiferromagnetic (AFM)
orders has been realized by various means, applicably appreciated
functionalities on the readout side of AFM-based devices are urgently desired.
Here, we report the remarkably enhanced anisotropic magnetoresistance (AMR) as
giant as ~ 160% in a simple resistor structure made of AFM Sr2IrO4 without
auxiliary reference layer. The underlying mechanism for the giant AMR is an
indispensable combination of atomic scale giant-MR-like effect and
magnetocrystalline anisotropy energy, which was not accessed earlier.
Furthermore, we demonstrate the bistable nonvolatile memory states that can be
switched in-situ without the inconvenient heat-assisted procedure, and robustly
preserved even at zero magnetic field, due to the modified interlayer coupling
by 1% Ga-doping in Sr2IrO4. These findings represent a straightforward step
toward the AFM spintronic devices.
