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Half-metallic ferromagnetic Heusler alloys having high spin polarization are promising candidates to realize large magnetoresistance (MR) ratio and high spin-transfer torque (STT) efficiency in next-generation spintronic devices. Since the Heusler alloy properties are sensitive to composition, optimizing the composition is crucial for enhancing device performance. Here, we report the fabrication of high-performance current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices using Co2MnxFe1−xGe (0 ≤ x ≤ 1) Heusler alloy, employing a high-throughput and detailed composition optimization method. The method combined composition-gradient films and local measurements to enable the composition variation from Co2FeGe to Co2MnGe to be efficiently studied on a single library sample with a small composition interval. The CPP-GMR devices fabricated from stacks annealed at 250○C showed a clear composition dependence of MR with the maximum of MR ratio ∼38% in the Mn-rich region of x = 0.85. By increasing the annealing temperature to 350○C, the MR ratio increased to ∼45% along with high STT efficiency ∼0.6 in the broad composition range of 0.2 ≤ x ≤ 0.7. The optimal composition for the highest MR changed with annealing temperature because of the stability of the GMR stack being higher in the lower x range. The record high MR for the all-metal CPP-GMRdevices, at low annealing temperature of 250○C was achieved by the detailed composition optimization. These results present the high potential of Co2MnxFe1−xGe and provide a comprehensive guidance on the composition optimization for achieving large MR ratio and high STT efficiency in the CPP-GMR devices.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: Spin-transfer-torque, Spintronic devices, Giant magnetoimpedance materials

Date published: 2024-11-01

Publisher: AIP Publishing

Journal:

• APL Materials (ISSN: 2166532X) vol. 12 issue. 11 111114

Funding:

• Advanced Storage Research Consortium
• Japan Science and Technology Agency JPMJCR2101
• MEXT Program: Data Creation and Utilization Type Material Research and Development JPMXP1122715503
• MEXT Intiative to Establish Next Generation Novel Intergrated Circuits Centers JPJ011438

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5289

First published URL: https://doi.org/10.1063/5.0226638

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Updated at: 2025-03-14 13:30:16 +0900

Published on MDR: 2025-01-22 16:30:16 +0900