Spin-orbit coupling, photoemission and light absorption from first-principles calculations

Prof Cheol-Hwan Park. Department of Physics and Astronomy, Seoul National University

A theoretical prediction [1] that the spin polarization of photoelectrons emitted from a topological insulator is highly tunable such that almost 100 % polarization along any arbitrary direction can be achieved by tuning the polarization of light was followed by a number of independent experimental confirmations [2-5].This photo-induced spin modulation phenomenon involving topological insulators suggests a new kind of spin-polarized electron sources [2]; however, there are some experimental results that cannot be explained by previous theoretical descriptions [1]. In this presentation, I will also discuss our recent theoretical investigation of the photoemission process from topological insulators [6] and interpret the recent experimental observations [2, 4]. Last, I will discuss how the electronic structure, photoemission and optical processes are affected by spin-orbit coupling [7].

[1] C.-H. Park, S. G. Louie, Phys. Rev. Lett. 109, 097601 (2012).
[2] C. Jozwiak et al., Nat. Phys. 9, 293 (2013).
[3] Z.-H. Zhu et al., Phys. Rev. Lett. 112, 076802 (2014).
[4] Z. Xie et al., Nat. Commun. 5, 3382 (2014).
[5] J. Sánchez-Barriga et al., Phys. Rev. X 4, 011046 (2014).
[6] Ji Hoon Ryoo and C.-H. Park, Phys. Rev. B 93, 085419 (2016).
[7] Tae Yoon Kim and C.-H. Park, unpublished.

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