Magnetization alignment in spin-transfer-torque magnetic random-access memory

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Hauptverfasser: Terko, Afan, Lertzman-Lepofsky, George, Suess, Dieter, Abert, Claas, Girt, Erol
Format: Preprint
Veröffentlicht: 2026
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author Terko, Afan
Lertzman-Lepofsky, George
Suess, Dieter
Abert, Claas
Girt, Erol
author_facet Terko, Afan
Lertzman-Lepofsky, George
Suess, Dieter
Abert, Claas
Girt, Erol
contents Reliable operation of perpendicular spin-transfer-torque magnetic random-access memory (p-STT-MRAM) requires control of magnetic alignment within the synthetic antiferromagnet (SAF) reference layer. At nanopillar dimensions, however, devices can exhibit magnetic states that are absent in extended thin films. We present a systematic micromagnetic study of 30 nm-diameter three-layer p-STT-MRAM nanopillars using experimentally motivated material parameters, and map equilibrium states as functions of bilinear and biquadratic interlayer exchange coupling. Phase diagrams show that introducing asymmetry between the SAF layers in saturation magnetization, anisotropy, and thickness reduces the coupling strength required to stabilize antiparallel SAF states and suppress competing configurations. Minimum-energy path calculations show that, for noncollinear antiparallel SAF states, increasing SAF asymmetry can raise SAF reversal barriers while lowering the free-layer barrier; this trade-off is absent for collinear antiparallel SAF states. Stray fields also significantly modify both SAF and free-layer energy barriers. To support the design of p-STT-MRAM devices with either collinear or noncollinear antiparallel SAF reference states, we publicly release the simulation dataset covering 4374 distinct device configurations.
format Preprint
id arxiv_https___arxiv_org_abs_2605_09201
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Magnetization alignment in spin-transfer-torque magnetic random-access memory
Terko, Afan
Lertzman-Lepofsky, George
Suess, Dieter
Abert, Claas
Girt, Erol
Mesoscale and Nanoscale Physics
Reliable operation of perpendicular spin-transfer-torque magnetic random-access memory (p-STT-MRAM) requires control of magnetic alignment within the synthetic antiferromagnet (SAF) reference layer. At nanopillar dimensions, however, devices can exhibit magnetic states that are absent in extended thin films. We present a systematic micromagnetic study of 30 nm-diameter three-layer p-STT-MRAM nanopillars using experimentally motivated material parameters, and map equilibrium states as functions of bilinear and biquadratic interlayer exchange coupling. Phase diagrams show that introducing asymmetry between the SAF layers in saturation magnetization, anisotropy, and thickness reduces the coupling strength required to stabilize antiparallel SAF states and suppress competing configurations. Minimum-energy path calculations show that, for noncollinear antiparallel SAF states, increasing SAF asymmetry can raise SAF reversal barriers while lowering the free-layer barrier; this trade-off is absent for collinear antiparallel SAF states. Stray fields also significantly modify both SAF and free-layer energy barriers. To support the design of p-STT-MRAM devices with either collinear or noncollinear antiparallel SAF reference states, we publicly release the simulation dataset covering 4374 distinct device configurations.
title Magnetization alignment in spin-transfer-torque magnetic random-access memory
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2605.09201