EXCHANGE BIAS IN IrMn₃/Py BILAYERS

Recently antiferromagnets have gained increased interest as active components for spintronics due to their intrinsic high frequency dynamcis and resulting zero net magnetic moment. One such material is IrMn₃ with the magnetic moments forming a triangular structure in the (111) planes and a giant magnetocrystalline anisotropy energy of 10 meV per formula unit. We prepared films of IrMn₃ on different substrates {[001]MgO, [0001]Al₂O₃ and Si}. Since spin-orbit torques are most pronounced for [100] oriented IrMn₃ we investigated the temperature and cooling field dependence of exchange bias. X-ray diffraction shows predominantly [100] crystallographic orientations, with also a small contribution due to [111] oriented grains. Magnetometry measurements using a quantum design superconducting quantum interference device (SQUID) show that the exchange bias decreases with increasing temperature and an anisotropy of the coercivity with in-plane field direction.