Modulating Spin Relaxation with Light and a Novel Spintronic Room Temperature Infrared Photodetector

We report modulating the spin relaxation rate in an InSb nanowire with infrared (IR) light. The nanowire is fashioned into a spin valve with cobalt and nickel contacts using electrochemical self-assembly. The spin relaxation length is long in the dark since \textasciitilde 96{\%} of the electrons occupy the lowest conduction subband at room temperature, which results in near elimination of the D'yakonov-Perel' (DP) spin relaxation. Under IR illumination, electrons are excited to higher subbands by IR photons, resulting in the revival of the DP relaxation and a threefold shortening of the spin relaxation length [1]. This changes the resistance of the spin valve and therefore has applications in a novel spintronic IR photodetector that can ideally work at room temperature with infinite light-to-dark contrast ratio, infinite detectivity and zero dark current if all other spin relaxation mechanisms are eliminated and spins can be injected into the nanowire and detected with 100{\%} efficiency. This work is supported by the NSF under grant CMMI-1301013. [1] M. I. Hossain, et al., Nanotechnology, \underline {26}, 281001(2015)