%0 Journal Article
%K Temperature
%K Faraday effect
%K Perovskite
%K Probes
%K Polarization
%K Nanotechnology
%K Magnetic moments
%K Spin polarization
%K Rotation
%K Magnetoelectronics
%K Semiconductor quantum wells
%K Electrospinning
%K Light emission
%K Pinch effect
%K Carrier diffusion length
%K Electron spin polarization
%K Electron-spin relaxation
%K Low temperature solutions
%K Photoinduced magnetization
%K Polycrystalline perovskite
%K Pump probe
%K Time-resolved Faraday rotation
%K Spin dynamics
%A D Giovanni
%A H Ma
%A J Chua
%A M Grätzel
%A Ramamoorthy Ramesh
%A S Mhaisalkar
%A N Mathews
%A T.C Sum
%B Nano Letters
%D 2015
%G eng
%I American Chemical Society
%P 1553-1558
%R 10.1021/nl5039314
%T Highly spin-polarized carrier dynamics and ultralarge photoinduced magnetization in CH3NH3PbI3 perovskite thin films
%V 15
%X 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°/m at 200 K (at wavelength γ = 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. © 2015 American Chemical Society.