Research ArticleSPINTRONICS

Observation of current-induced, long-lived persistent spin polarization in a topological insulator: A rechargeable spin battery

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Science Advances  14 Apr 2017:
Vol. 3, no. 4, e1602531
DOI: 10.1126/sciadv.1602531

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Abstract

Topological insulators (TIs), with their helically spin-momentum–locked topological surface states (TSSs), are considered promising for spintronics applications. Several recent experiments in TIs have demonstrated a current-induced electronic spin polarization that may be used for all-electrical spin generation and injection. We report spin potentiometric measurements in TIs that have revealed a long-lived persistent electron spin polarization even at zero current. Unaffected by a small bias current and persisting for several days at low temperature, the spin polarization can be induced and reversed by a large “writing” current applied for an extended time. Although the exact mechanism responsible for the observed long-lived persistent spin polarization remains to be better understood, we speculate on possible roles played by nuclear spins hyperfine-coupled to TSS electrons and dynamically polarized by the spin-helical writing current. Such an electrically controlled persistent spin polarization with unprecedented long lifetime could enable a rechargeable spin battery and rewritable spin memory for potential applications in spintronics and quantum information.

Keywords
  • Topological insulators
  • topological surface states
  • spintronics
  • spin polarization
  • spin life time
  • nuclear spin

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