Strong perpendicular magnetic anisotropy energy density at Fe alloy/HfO2 interfaces

Abstract

We report on the perpendicular magnetic anisotropy (PMA) behavior of heavy metal (HM)/ Fe alloy/MgO thin film heterostructures after an ultrathin HfO2 passivation layer is inserted between the Fe alloy and the MgO. This is accomplished by depositing one to two atomic layers of Hf onto the Fe alloy before the subsequent rf sputter deposition of the MgO layer. This Hf layer is fully oxidized during the subsequent deposition of the MgO layer, as confirmed by X-ray photoelectron spectroscopy measurements. As the result a strong interfacial perpendicular anisotropy energy density can be achieved without any post-fabrication annealing treatment, for example 1.7 erg/cm^2 for the Ta/Fe60Co20B20/HfO2/MgO heterostructure. Depending on the HM, further enhancements of the PMA can be realized by thermal annealing to at least 400C. We show that ultra-thin HfO2 layers offer a range of options for enhancing the magnetic properties of magnetic heterostructures for spintronics applications.

16 pages; 3 figures

References in corpus (3)

• The nature of domain walls in ultrathin ferromagnets revealed by scanning nanomagnetometry
• Enhancement of the Anti-Damping Spin Torque Efficacy of Platinum by Interface Modification
• On the origin of field-like spin-orbit torques in heavy metal-ferromagnet-oxide thin film heterostructures

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