1. Department of Physics and the Center of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China 2. Institute of Textiles and Clothing, Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China 3. The University of Hong Kong Shenzhen Institute of Research and Innovation, Shenzhen 518057, China 4. Center for the Physics of Materials and Department of Physics, McGill University, Montreal, PQ, Canada, H3A 2T8
We report an extensive first-principles investigation of impurity-induced device-to-device variability of spin-polarized quantum tunneling through Fe/MgO/Fe magnetic tunnel junctions (MTJ). In particular, we calculated the tunnel magnetoresistance ratio (TMR) and the average values and variances of the currents and spin transfer torque (STT) of an interfacially doped Fe/MgO/Fe MTJ. Further, we predicted that N-doped MgO can improve the performance of a doped Fe/MgO/Fe MTJ. Our firstprinciples calculations of the fluctuations of the on/off currents and STT provide vital information for future predictions of the long-term reliability of spintronic devices, which is imperative for high-volume production.
International technology roadmap for semiconductors,
2
A. Asenov, Random dopant induced threshold voltage lowering and fluctuations in sub-0.1 mm MOSFET’s: A 3D “atomistic” simulation study, IEEE Trans. Electron Dev. 45(12), 2505 (1998)
https://doi.org/10.1109/16.735728
3
P. M. Koenraad and M. E. Flatté, Single dopants in semiconductors, Nat. Mater. 10(2), 91 (2011)
https://doi.org/10.1038/nmat2940
V. P. Georgiev, E. A. Towie, and A. Asenov, Impact of precisely positioned dopants on the performance of an ultimate silicon nanowire transistor: A full threedimensional NEGF simulation study, IEEE Trans. Electron Dev. 60(3), 965 (2013)
https://doi.org/10.1109/TED.2013.2238944
6
S. Ikeda, J. Hayakawa, Y. M. Lee, F. Matsukura, Y. Ohno, T. Hanyu, and H. Ohno, Magnetic tunnel junctions for spintronic memories and beyond, IEEE Trans. Electron Dev. 54(5), 991 (2007)
https://doi.org/10.1109/TED.2007.894617
S. S. P. Parkin, C. Kaiser, A. Panchula, P. M. Rice, B. Hughes, M. Samant, and S. H. Yang, Giant tunnelling magnetoresistance at room temperature with MgO (100) tunnel barriers, Nat. Mater. 3(12), 862 (2004)
https://doi.org/10.1038/nmat1256
9
S. Yuasa, T. Nagahama, A. Fukushima, Y. Suzuki, and K. Ando, Giant room-temperature magnetoresistance in single-crystal Fe/MgO/Fe magnetic tunnel junctions, Nat. Mater. 3(12), 868 (2004)
https://doi.org/10.1038/nmat1257
10
D. Waldron, P. Haney, B. Larade, A. MacDonald, and H. Guo, Nonlinear spin current and magnetoresistance of molecular tunnel junctions, Phys. Rev. Lett. 96(16), 166804 (2006)
https://doi.org/10.1103/PhysRevLett.96.166804
11
Y. Ke, K. Xia, and H. Guo, Oxygen-vacancy-induced diffusive scattering in Fe/MgO/Fe magnetic tunnel junctions, Phys. Rev. Lett. 105(23), 236801 (2010)
https://doi.org/10.1103/PhysRevLett.105.236801
12
S. S. P. Parkin, C. Kaiser, A. Panchula, P. M. Rice, B. Hughes, M. Samant, and S. H. Yang, Giant tunnelling magnetoresistance at room temperature with MgO (100) tunnel barriers, Nat. Mater. 3(12), 862 (2004)
https://doi.org/10.1038/nmat1256
13
S. Yuasa, T. Nagahama, A. Fukushima, Y. Suzuki, and K. Ando, Giant room-temperature magnetoresistance in single-crystal Fe/MgO/Fe magnetic tunnel junctions, Nat. Mater. 3(12), 868 (2004)
https://doi.org/10.1038/nmat1257
W. H. Butler, X. G. Zhang, T. C. Schulthess, and J. M. Maclaren, Spin-dependent tunneling conductance of FejMgOjFe sandwiches, Phys. Rev. B 63(5), 054416 (2001)
https://doi.org/10.1103/PhysRevB.63.054416
17
J. Zhuang and J. Wang, Conductance fluctuation and shot noise in disordered graphene systems, a perturbation expansion approach, J. Appl. Phys. 114(6), 063708 (2013)
https://doi.org/10.1063/1.4817885
18
Y. Zhu, L. Liu, and H. Guo, Quantum transport theory with nonequilibrium coherent potentials, Phys. Rev. B 88(20), 205415 (2013)
https://doi.org/10.1103/PhysRevB.88.205415
19
Y. Zhu, L. Liu, and H. Guo, Green’s function theory for predicting device-to-device variability, Phys. Rev. B 88(8), 085420 (2013)
https://doi.org/10.1103/PhysRevB.88.085420
Y. Ke, K. Xia, and H. Guo, Disorder scattering in magnetic tunnel junctions: Theory of nonequilibrium vertex correction, Phys. Rev. Lett. 100(16), 166805 (2008)
https://doi.org/10.1103/PhysRevLett.100.166805
22
J. Maassen, M. Harb, V. Michaud-Rioux, Y. Zhu, and H. Guo, Quantum transport modeling from first principles, Proc. IEEE 101(2), 518 (2013)
https://doi.org/10.1109/JPROC.2012.2197810
23
Y. Zhu and L. Liu, Atomistic Simulation of Quantum Transport in Nanoelectronic Devices, World Scientific, 2016
https://doi.org/10.1142/10072
24
J. Taylor, H. Guo, and J. Wang, Ab initiomodeling of open systems: Charge transfer, electron conduction, and molecular switching of a C60 device, Phys. Rev. B 63, 121104(R) (2001)
25
J. Taylor, H. Guo, and J. Wang, Ab initiomodeling of quantum transport properties of molecular electronic devices, Phys. Rev. B 63(24), 245407 (2001)
https://doi.org/10.1103/PhysRevB.63.245407
26
S. I. Kiselev, J. C. Sankey, I. N. Krivorotov, N. C. Emley, M. Rinkoski, C. Perez, R. A. Buhrman, and D. C. Ralph, Current-induced nanomagnet dynamics for magnetic fields perpendicular to the sample plane, Phys. Rev. Lett. 93(3), 036601 (2004)
https://doi.org/10.1103/PhysRevLett.93.036601
P. M. Haney, R. A. Duine, A. S. Nunez, and A. H. Mac-Donald, Current-induced torques in magnetic metals: Beyond spin-transfer, J. Magn. Magn. Mater. 320(7), 1300 (2008)
https://doi.org/10.1016/j.jmmm.2007.12.020
29
I. Theodonis, N. Kioussis, A. Kalitsov, M. Chshiev, and W. H. Butler, Anomalous bias dependence of spin torque in magnetic tunnel junctions, Phys. Rev. Lett. 97(23), 237205 (2006)
https://doi.org/10.1103/PhysRevLett.97.237205
30
X. Jia, K. Xia, Y. Ke, and H. Guo, Nonlinear bias dependence of spin-transfer torque from atomic first principles, Phys. Rev. B 84(1), 014401 (2011)
https://doi.org/10.1103/PhysRevB.84.014401
31
I. Turek, V. Drchal, J. Kudrnovský, M. Šob, and P. Weinberger, Electronic Structure of the Disordered Alloys, Surfaces, and Interfaces, Boston: Kluwer, 1977
32
J. Kudrnovský, V. Drchal, and J. Maek, Canonical description of electron states in random alloys, Phys. Rev. B 35(5), 2487 (1987)
https://doi.org/10.1103/PhysRevB.35.2487
33
D. Liu, X. Han, and H. Guo, Junction resistance, tunnel magnetoresistance ratio, and spin-transfer torque in Zndoped magnetic tunnel junctions, Phys. Rev. B 85(24), 245436 (2012)
https://doi.org/10.1103/PhysRevB.85.245436