FU-03 Nondestructive Ferromagnetic Resonance as a Tool to Evaluate Quality in Samples with Perpendicular Magnetic Anisotropy
Creators: Allison Harpel
Md Toaha Anas
Alex Wege
Rhonda Franklin
Bethanie Stadler
Publisher: name: IEEE
Year: 2025

Samples with perpendicular magnetic anisotropy (PMA) are particularly popular today for various computing and spintronic applications [1], [2], [3], [4], but to make the transition from research labs to industry, tight quality control is needed. However, because many measurements have factors such as porosity and magnetization that scale together (e.g.: measurements of total sample magnetization), there is a dearth of quick, non-destructive, low-cost methods to effectively quantify quality. Here, to create a wide range of controlled samples with perpendicular magnetic anisotropy, MNWs were fabricated in anodized aluminum oxide templates [5]. The deposition quality is evaluated by common, but qualitative or semi-quantitative methods, which are then compared to the quantitative values for fill factor (FF) and saturation magnetization (MS) measured using a nondestructive ferromagnetic resonance (FMR) method. Of note, seeding Co MNWs with Cu before fabrication is shown to improve FF while maintaining MNW quality, demonstrating that this method has a sensitivity to FF and MS that allows for measurement differentiation at practicable values. For the seeded sample, FMR measured FF at 12.3 ± 0.4 %, with a MS of 1.64 ± 0.10 T. For the sample without a seed, FMR measured FF at 9.0 ± 0.4% with a MS of 1.62 ± 0.13 T. These quantitative measurements were corroborated by all the qualitative and semiquantitative results, indicating that nondestructive FMR is a viable method to quantify fill factor and quickly evaluate the quality of templated MNWs. Importantly, fill factor (or sample porosity) and magnetization can be separately analyzed by this method.References: [1] D. Apalkov, B. Dieny, and J. M. Slaughter, Proc. IEEE, vol. 104, no. 10, pp. 1796–1830, (2016). [2] B. Dieny and M. Chshiev, Rev. Mod. Phys., vol. 89, no. 2, p. 025008, (2017). [3] I. Tudosa, J. A. Katine, S. Mangin, and E. E. Fullerton, IEEE Trans. Magn., vol. 46, no. 6, pp. 2328–2330, (2010). [4] J. J. Bauer et al., Adv Elect Materials, vol. 6, no. 1, p. 1900820, (2020). [5] L. Sun, Y. Hao, C.-L. Chien, and P. C. Searson, IBM J. Res. & Dev., vol. 49, no. 1, pp. 79–102, (2005).
Samples with perpendicular magnetic anisotropy (PMA) are particularly popular today for various computing and spintronic applications [1], [2], [3], [4], but to make the transition from research labs to industry, tight quality control is needed. However, because many measurements have factors such as porosity and magnetization that scale together (e.g.: measurements of total sample magnetization), there is a dearth of quick, non-destructive, low-cost methods to effectively quantify quality. Here, to create a wide range of controlled samples with perpendicular magnetic anisotropy, MNWs were fabricated in anodized aluminum oxide templates [5]. The deposition quality is evaluated by common, but qualitative or semi-quantitative methods, which are then compared to the quantitative values for fill factor (FF) and saturation magnetization (MS) measured using a nondestructive ferromagnetic resonance (FMR) method. Of note, seeding Co MNWs with Cu before fabrication is shown to improve FF while maintaining MNW quality, demonstrating that this method has a sensitivity to FF and MS that allows for measurement differentiation at practicable values. For the seeded sample, FMR measured FF at 12.3 ± 0.4 %, with a MS of 1.64 ± 0.10 T. For the sample without a seed, FMR measured FF at 9.0 ± 0.4% with a MS of 1.62 ± 0.13 T. These quantitative measurements were corroborated by all the qualitative and semiquantitative results, indicating that nondestructive FMR is a viable method to quantify fill factor and quickly evaluate the quality of templated MNWs. Importantly, fill factor (or sample porosity) and magnetization can be separately analyzed by this method.References: [1] D. Apalkov, B. Dieny, and J. M. Slaughter, Proc. IEEE, vol. 104, no. 10, pp. 1796–1830, (2016). [2] B. Dieny and M. Chshiev, Rev. Mod. Phys., vol. 89, no. 2, p. 025008, (2017). [3] I. Tudosa, J. A. Katine, S. Mangin, and E. E. Fullerton, IEEE Trans. Magn., vol. 46, no. 6, pp. 2328–2330, (2010). [4] J. J. Bauer et al., Adv Elect Materials, vol. 6, no. 1, p. 1900820, (2020). [5] L. Sun, Y. Hao, C.-L. Chien, and P. C. Searson, IBM J. Res. & Dev., vol. 49, no. 1, pp. 79–102, (2005).