Spin Transport Calculation in Novel Nm-Scale Magnetic Junctions
Yu-Hui Tang (唐毓慧)1*
1Physics, National Central University, Taoyuan City, Taiwan
* presenting author:Yu-Hui Tang, email:yhtang@cc.ncu.edu.tw
Recently, our theoretical researches focus on searching for novel nm-scale ferromagnetic/barrier/ferromagnetic (FM/B/FM) magnetic tunnel junctions (MTJs) with superior spin transport properties by choosing semiconductor [1], spin-filter material [2], and single molecule [3] as the central barriers, which may inspire further experimentations in spintronics applications. However, the main difficulty in the spin transport study of these complex heterojunctions is the lack of reliable simulation tools. We have developed the tight-binding model, derived the general expression of non-collinear spin torque effect, and tested various kinds of first-principles spin-polarized transport calculation tools for conventional MgO-based MTJs [4,5], Au/Oligothiophene/Au junction [6], and single-molecule magnetic junctions with different linker and central molecules. Finally, we’ve successfully combined the first-principles calculation with the tight-binding model and the non-equilibrium Keldysh Green’s function method not only to calculate the collinear spin polarized current densities but also to further predict the non-collinear spin torque effect via our newly derived general expressions. This in turn may resolve the current self-consistence difficulties of first-principles spin-polarized transport calculations for complex heterojunction structures in non-collinear magnetic configuration. (Contract No. NSC 102-2112-M-008-004-MY3 and MOST 105-2112-M-008-010- )

[1] Y. –H. Tang, F. –C. Chu, and N. Kioussis, Sci. Rep. 5, 11341 (2015).
[2] Y. –H. Tang and F. –C. Chu, J. Appl. Phys. 117, 093901 (2015).
[3] Y. –H. Tang et al., J. Phys. Chem. C 120, 692 (2016)
[4] Y. –H. Tang et al., Phys. Rev. Lett. 103, 057206 (2009).
[5] Y. –H. Tang et al., Phys. Rev. B 81, 054437 (2010).
[6] Y. –H. Tang et al., J. Phys. Chem. C 115, 25105 (2011)

Keywords: Spin tranport, magnetic junction, spin torque, magnetoresistance, spin injection