Isothermal tuning of magnetic coercivity in NiFe/NiO/[Co/Pt] heterostructures with orthogonal easy axes

Heterostructures of NiFe/NiO/[Co/Pt] with mutually orthogonal easy axes allow for isothermal tuning of the magnetic coercivity at room temperature with no associated shift in the hysteresis loop along the applied field axis. This is in contrast to what is typically seen in exchange biased heterostructures. The NiFe coercivity is enhanced from 14.5 to 105 Oe through the application of moderate dc magnetic fields of < 3 kOe. This enhancement is completely reset with the application of a similarly sized dc magnetic field perpendicular to the film. The pinning of the antiferromagnetic NiO interlayer (i.e., blocking temperature, which is expected to be well below 50K at this thickness in the absence of adjacent magnetic layers) is greatly enhanced and influenced by the in-plane magnetization of both the NiFe and [Co/Pt]. In addition, these heterostructures show unique high and low-field training effects due to alignment of [Co/Pt] stripe domains. This dynamic, yet predictable, behavior where the coercivity is isothermally tuned without any permanent structural/chemical modifications has potential uses in advanced magnetic logic/storage, as well as tuning the interfacial coupling in spintronic applications. (C) 2015 AIP Publishing LLC.