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Abstract
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The spin‑photo current in single layer stanene and germanene under a linearly polarized light is
theoretically investigated based on the tight‑binding Hamiltonian combined with the nonequilibrium
Green’s function at room temperature. The results show that by considering the simultaneous
effect of the linear illumination and a vertical external electric field without any magnetic exchange
element, pure spin‑photo current without charge current is generated in two‑dimensional lattices
with a large intrinsic spin–orbit coupling. The necessity of enhanced spin life‑time for detection of
spin polarization can be explained by spin‑valley locking concept. Spin‑valley locking arises in buckled
two‑dimensional materials as a result of the large spin–orbit coupling and electric‑field reversible
valley spin polarization. Equal absorption of the linearly illumination at both valleys with different spin
polarization, leads to pure spin‑photo current injection. In addition, an acceptable photoresponsivity
has been reported in a broad range of photon energy. The numerical results indicate high quantum
efficiency with a maximum of nearly 83% and 50% for stanene and germanene, respectively. This work
may pave theoretical reference toward design of new spin‑optoelectronic devices based on satanene
and germanene junctions with high performance.
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