Electric field-induced magnetization reversal in a perpendicular-anisotropy CoFeB-MgO magnetic tunnel junction Appl. Phys. Lett. 101, 122403 (2012) Spin transfer torque devices utilizing the giant spin Hall effect of tungsten Appl. Phys. Lett. 101, 122404 (2012) Modifications of magnetic anisotropy and magnetization reversal in [Co0.4nm/Pd0.7nm]50 multilayers induced by 10keV-He ion bombardment J. Appl. Phys. 112, 063901 (2012) Properties of magnetic nickel/porous-silicon composite powders AIP Advances 2, 032167 (2012) Additional information on J. Appl. Phys.We have investigated the thermal stability of the exchange biasing interaction in antiferromagnetic/ ferromagnetic bilayers of Ir 19 Mn 81 and Ni 80 Fe 20 or Co 90 Fe 10 . The exchange-biasing field and the coercive field were found to depend strongly on the thickness of the Ir 19 Mn 81 layer and on the crystallographic texture of the bilayer. The exchange-biasing field at room temperature has a maximum at 4 nm Ir 19 Mn 81 layer thickness and then decreases for increasing Ir 19 Mn 81 layer thickness. This coincides quite well with the thickness dependence of the ͑111͒ texture measured in Ir 19 Mn 81 layers. Removing the Ta seed layer resulted in the disappearance of the ͑111͒ texture and at the same time the exchange-biasing field decreased for all Ir 19 Mn 81 layer thicknesses. For films with a Ta seed layer and 8 nm Ir 19 Mn 81 or more, we have found a blocking temperature of 560 K, decreasing with decreasing Ir 19 Mn 81 layer thickness to around room temperature for 2 nm Ir 19 Mn 81 . Removing the Ta seed layer resulted in a decrease of the blocking temperature for all layer thicknesses investigated. We have concluded that the ͑111͒ texture is an important factor governing the size of the exchange-biasing field and the thermal stability.

We have investigated the strength and the thermal stability of Ir–Mn (18 at. % Ir) as an exchange biasing material for Ni80Fe20 and Co90Fe10, for configurations with the Ir–Mn layer both below and above the ferromagnetic (F) layer. The highest interfacial exchange energy (Jeb=0.13 mJ/m2 at 300 K) was found for 10 nm Ir–Mn deposited above a Co90Fe10 layer. For all configurations investigated the blocking temperature was approximately 560 K. For 10 or 30 nm Ir–Mn above and for 30 nm Ir–Mn below the F layer a remarkable decrease of the exchange biasing at room temperature was found after heating the film, whereas such an effect was not observed for a 10 nm thick Ir–Mn layer deposited below the F layer. This observation, in combination with the results of a relaxation experiment and the lack of experimental evidence for structural changes upon heating, suggests that heating can induce an irreversible change in the magnetic structure of Ir–Mn layers.

No abstract

No abstract

No abstract