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Chiral tunneling of topological states: towards the efficient generation of spin current using spin-momentum locking
K M Masum Habib1, Redwan N Sajjad1, Avik W Ghosh1
1Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, Virginia 22904, USA.
Abstract:
We show that the interplay between chiral tunneling and spin-momentum locking of helical surface states leads to spin amplification and filtering in a 3D topological insulator (TI). Our calculations show that the chiral tunneling across a TI pn junction allows normally incident electrons to transmit, while the rest are reflected with their spins flipped due to spin-momentum locking. The net result is that the spin current is enhanced while the dissipative charge current is simultaneously suppressed, leading to an extremely large, gate-tunable spin-to-charge current ratio (∼20) at the reflected end. At the transmitted end, the ratio stays close to 1 and the electrons are completely spin polarized.
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