Influence of Ta insertions on the magnetic properties of MgO/CoFeB/MgO films probed by ferromagnetic resonance

TL;DR

This study demonstrates that inserting ultra-thin Ta layers in MgO/CoFeB/MgO films reduces magnetic damping and maintains perpendicular magnetization, though it does not enhance magnetic anisotropy.

Contribution

It reveals how Ta insertions influence magnetic damping and anisotropy in MgO/CoFeB/MgO films, providing insights for optimizing magnetic properties in spintronic devices.

Findings

Achieved low Gilbert damping ({}  0.006) with Ta insertions.

More Ta insertions allow thicker CoFeB to stay perpendicular.

Areal magnetic anisotropy does not improve with additional Ta layers.

Abstract

We show by vector network analyzer ferromagnetic resonance measurements that low Gilbert damping {\alpha} down to 0.006 can be achieved in perpendicularly magnetized MgO/CoFeB/MgO thin films with ultra-thin insertions of Ta in the CoFeB layer. While increasing the number of Ta insertions allows thicker CoFeB layers to remain perpendicular, the effective areal magnetic anisotropy does not improve with more insertions, and also comes with an increase in {\alpha}.