Quantitative Visualization of Thermally Enhanced Perpendicular Shape Anisotropy STT-MRAM Nanopillars

Perpendicular shape anisotropy (PSA) offers a practical solution to downscale spin-transfer torque magnetoresistive random-access memory (STT-MRAM) beyond the sub-20 nm technology node while retaining thermal stability. However, our understanding of the thermomagnetic behavior of PSA-STT-MRAM is oft...

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Bibliographic Details
Published in:Nano letters 2022-05, Vol.22 (10), p.4000-4005
Main Authors: Almeida, Trevor P., Lequeux, Steven, Palomino, Alvaro, Sousa, Ricardo C., Fruchart, Olivier, Prejbeanu, Ioan-Lucian, Dieny, Bernard, Masseboeuf, Aurélien, Cooper, David
Format: Article
Language:English
Subjects:
Condensed Matter
Materials Science
Physics
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Summary:Perpendicular shape anisotropy (PSA) offers a practical solution to downscale spin-transfer torque magnetoresistive random-access memory (STT-MRAM) beyond the sub-20 nm technology node while retaining thermal stability. However, our understanding of the thermomagnetic behavior of PSA-STT-MRAM is often indirect, relying on magnetoresistance measurements and micromagnetic modeling. Here, the magnetism of a NiFe PSA-STT-MRAM nanopillar is investigated using off-axis electron holography, providing spatially resolved magnetic information as a function of temperature. Magnetic induction maps reveal the micromagnetic configuration of the NiFe storage layer (∼60 nm high, ≤20 nm diameter), confirming the PSA induced by its 3:1 aspect ratio. In situ heating demonstrates that the PSA of the storage layer is maintained up to at least 250 °C, and direct quantitative measurements reveal a moderate decrease of magnetic induction. Hence, this study shows explicitly that PSA provides significant stability in STT-MRAM applications that require reliable performance over a range of operating temperatures.
ISSN:1530-6984
1530-6992
DOI:10.1021/acs.nanolett.2c00597