Hanle effect near boundaries: Diffusion-induced lineshape inhomogeneity

The Hanle effect describes suppression of spin polarization due to precession in a magnetic field. This is a standard spintronics tool and it gives access to the spin lifetime of samples in which spins are generated homogeneously. We examine the Hanle effect when spins are generated at a boundary of a diffusive sample by the extrinsic spin Hall effect. We show that the Hanle curve is spatially dependent and that the ``apparent'' spin lifetime, given by its inverse half-width, is shorter near the boundary even if the spin relaxation rate is homogeneous.