Highly Spin-Polarized Carrier Dynamics and Ultra large Photoinduced Magnetization in CH(3)NH(3)Pbl(3) Perovskite Thin Films

Low-temperature solution-processed organic-inorganic halide perovskite CH3NH3PbI3 has demonstrated great potential for photovoltaics and light-emitting devices. Recent discoveries of long ambipolar carrier diffusion lengths and the prediction of the Rashba effect in CH3NH3PbI3, that possesses large spin-orbit coupling, also point to a novel semiconductor system with highly promising properties for spin-based applications. Through circular pump-probe measurements, we demonstrate that highly polarized electrons of total angular momentum (J) with an initial degree of polarization P-ini similar to 90% (i.e., -30% degree of electron spin polarization) can be photogenerated in perovskites. Time-resolved Faraday rotation measurements reveal photoinduced Faraday rotation as large as 10 degrees/mu m at 200 K (at wavelength lambda = 750 nm) from an ultrathin 70 nm film. These spin polarized carrier populations generated within the polycrystalline perovskite films, relax via intraband carrier spin-flip through the Elliot-Yafet mechanism. Through a simple two-level model, we elucidate the electron spin relaxation lifetime to be similar to 7 ps and that of the hole is similar to 1 ps. Our work highlights the potential of CH3NH3PbI3 as a new candidate for ultrafast spin switches in spintronics applications.

Published in:
Nano Letters, 15, 3, 1553-1558
Washington, American Chemical Society

 Record created 2015-05-29, last modified 2018-03-17

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