Tunable microwave magnetic properties in oblique deposited CoHf/Ta multilayers

In this work, the microwave magnetic properties of oblique deposited CoHf/Ta multilayers were investigated. The high frequency magnetic properties of CoHf/Ta multilayers showed different behaviors with oblique angle for different Ta interlayer thickness t. For example, when the Ta interlayer thickness fixed as 5.0 nm, the resonance frequency fr increased from 2.1 to 3.4 GHz with the oblique deposition angle θ changing from 10° to 30°. However, when the Ta layer fixed as 15.0 nm, the fr decreased from 2.5 to 1.7 GHz with the oblique deposition angle changing in the same range. The opposite behavior of the fr with θ is supposed to result from the existence of the Ta buffer layer, in which the thicker Ta interlayer may hinder the self-shadow effects of the CoHf magnetic layers.