VP14-01 L10 FeAu perpendicular magnetic tunnel junction: A DFT + NEGF study
Creators: Rouf Rahman Sheikh
Ram Krishna Ghosh
Publisher: name: IEEE
Year: 2025

This work examines the spin dynamic and transport properties of transition metal intermetallic alloy, L10 FeAu, using density functional theory (DFT) combined with the nonequilibrium Green's function (NEGF) technique. The motivation behind this work is driven by the potential application of this ferromagnet in spintronic devices, where it can act as a magnetic electrode material for MgO-based perpendicular magnetic tunnel junction (p-MTJ) for spin transfer torque magnetic random-access memory (STT-MRAM). Our analyses show several advantages of L10 FeAu, like large bulk magnetic anisotropy energy (1.20meV/f.u.), which contributes to higher thermal stability, relatively low Gilbert damping (0.0035), that helps to reduce the switching current and also has spin-polarized Δ1 bands on Fermi surface that can effectively provide higher tunneling magnetoresistance (TMR) for better read-operation. In our analysis, we find that the TMR of FeAu-based MTJs (having 0.9nm thick MgO barrier) is around 34000%, which is 8 times higher than that of our calculated conventional Fe-based p-MTJ with similar barrier thickness. It was also found that the RA product of FeAu MTJ is one order higher than that of Fe-based MTJs, which helps in improving switching efficiency; however, the switching voltage can also increase. Overall, the collective computations demonstrate the importance of L10 FeAu ferromagnetic material for future STT-MRAMs.References: 1. Gilmore, K., Idzerda, Y. U. & Stiles, M. D. Phys. Rev. Lett. 99, 027204 (2007). 2. Takanashi, K. et al. . Appl. Phys. Lett. 67, 1016 (1995). 3. Zhang, X. et al., Appl. Phys. Lett. 110, (2017). 4. Daalderop, G. H. O., Kelly, P. J. & Schuurmans, M. F. H. Phys. Rev. B 41, 11919–11937 (1990). 5. Galanakis, I., Alouani, M, H. Phys. Rev. B - Condens. Matter Mater. Phys. 62, 6475–6484 (2000). 6. Mahfouzi, F. & Kioussis,. Phys. Rev. B 98, (2018). 7. G. Hu et al., 2021 IEEE IEDM, San Francisco, CA, USA, 2021, pp. 2.5.1-2.5.4 8. C. Park et al., 2018 IEEE Symposium on VLSI Technology, Honolulu, HI, USA, 2018, pp. 185-186
This work examines the spin dynamic and transport properties of transition metal intermetallic alloy, L10 FeAu, using density functional theory (DFT) combined with the nonequilibrium Green's function (NEGF) technique. The motivation behind this work is driven by the potential application of this ferromagnet in spintronic devices, where it can act as a magnetic electrode material for MgO-based perpendicular magnetic tunnel junction (p-MTJ) for spin transfer torque magnetic random-access memory (STT-MRAM). Our analyses show several advantages of L10 FeAu, like large bulk magnetic anisotropy energy (1.20meV/f.u.), which contributes to higher thermal stability, relatively low Gilbert damping (0.0035), that helps to reduce the switching current and also has spin-polarized Δ1 bands on Fermi surface that can effectively provide higher tunneling magnetoresistance (TMR) for better read-operation. In our analysis, we find that the TMR of FeAu-based MTJs (having 0.9nm thick MgO barrier) is around 34000%, which is 8 times higher than that of our calculated conventional Fe-based p-MTJ with similar barrier thickness. It was also found that the RA product of FeAu MTJ is one order higher than that of Fe-based MTJs, which helps in improving switching efficiency; however, the switching voltage can also increase. Overall, the collective computations demonstrate the importance of L10 FeAu ferromagnetic material for future STT-MRAMs.References: 1. Gilmore, K., Idzerda, Y. U. & Stiles, M. D. Phys. Rev. Lett. 99, 027204 (2007). 2. Takanashi, K. et al. . Appl. Phys. Lett. 67, 1016 (1995). 3. Zhang, X. et al., Appl. Phys. Lett. 110, (2017). 4. Daalderop, G. H. O., Kelly, P. J. & Schuurmans, M. F. H. Phys. Rev. B 41, 11919–11937 (1990). 5. Galanakis, I., Alouani, M, H. Phys. Rev. B - Condens. Matter Mater. Phys. 62, 6475–6484 (2000). 6. Mahfouzi, F. & Kioussis,. Phys. Rev. B 98, (2018). 7. G. Hu et al., 2021 IEEE IEDM, San Francisco, CA, USA, 2021, pp. 2.5.1-2.5.4 8. C. Park et al., 2018 IEEE Symposium on VLSI Technology, Honolulu, HI, USA, 2018, pp. 185-186