Fermi level dependent spin pumping from a magnetic insulator into a topological insulator

Hailong Wang, James Kally, Cüneyt Sąhin, Tao Liu, Wilson Yanez, Eric J. Kamp, Anthony Richardella, Mingzhong Wu, Michael E. Flatté, Nitin Samarth

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Topological spintronics aims to exploit the spin-momentum locking in the helical surface states of topological insulators for spin-orbit torque devices. We address a fundamental question that still remains unresolved in this context: Does the topological surface state alone produce the largest values of spin-charge conversion efficiency or can the strongly spin-orbit coupled bulk states also contribute significantly? By studying the Fermi level dependence of spin pumping in topological insulator/ferrimagnetic insulator bilayers, we show that the spin Hall conductivity is constant when the Fermi level is tuned across the bulk band gap, consistent with a full bulk band calculation. The results suggest a different perspective, wherein "bulk-surface correspondence"allows spin-charge conversion to be simultaneously viewed either as coming from the full bulk band, or from spin-momentum locking of the surface state.

Original languageEnglish (US)
Article number012014
JournalPhysical Review Research
Issue number1
StatePublished - Aug 2019

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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