Topological insulators (TIs), with their helically spin-momentum-locked topological surface states (TSS), 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. Here, 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. While 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.
Yong P. Chen, "Observation of current-induced, long-lived persistent spin polarization in a topological insulator: a rechargeable spin battery (Conference Presentation)," Proc. SPIE 10357, Spintronics X, 103573A (Presented at SPIE Nanoscience + Engineering: August 10, 2017; Published: 19 September 2017); https://doi.org/10.1117/12.2278746.5581356081001.
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