title: Highly spin-polarized carrier dynamics and ultralarge photoinduced magnetization in CH3NH3PbI3 perovskite thin films.
abstract: 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 Pini ∼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°/μm at 200 K (at wavelength λ = 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 ∼7 ps and that of the hole is ∼1 ps. Our work highlights the potential of CH3NH3PbI3 as a new candidate for ultrafast spin switches in spintronics applications.
authors: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, Singapore 637371, Singapore.
authors: David
authors: D
authors: Giovanni
authors: Hong
authors: H
authors: Ma
authors: Julianto
authors: J
authors: Chua
authors: Michael
authors: M
authors: Grätzel
authors: Ramamoorthy
authors: R
authors: Ramesh
authors: Subodh
authors: S
authors: Mhaisalkar
authors: Nripan
authors: N
authors: Mathews
authors: Tze Chien
authors: TC
authors: Sum
keywords: Faraday rotation; Spintronics; circular pump−probe; spin dynamics; spin polarization