Spin resolved transverse electron focusing in wide leads due to diffuse collimation in InSb/InAlSb two-dimensional electron gases

Using the transverse electron focusing geometry, we report spin-resolved cyclotron motion in an InSb two-dimensional electron gas (2DEG). A zero field spin spitting$^{1}$ causes electrons from different spin subbands to have slightly different cyclotron radii in external field which manifest as a splitting in the first focusing peak.$^{2}$ Traditionally in focusing experiments, electrons are emitted and collected via quantum point contacts that host only a few open channels. We show that spin resolved electron focusing is observable in $wide$ leads with many open channels due to diffuse collimation of ballistic electrons emitted into the bulk 2DEG region. The results are compared to a semiclassical model$^{3}$ from which a Rashba-type spin-orbit coupling parameter of $\alpha = 5x10^{-11}$ eVm is deduced at 2 K. We compare these results to values determined from the beating of Shubnikov-de Haas oscillations.$^{4}$ We also present ballistic transport results extending over 3 $\mu$m.\\ $^{1}$A. M. Gilbertson, et al., Phys. Rev. B 77, 165335 (2008). $^{2}$L. P. Rokhinson, et al., Phys. Rev. Letts. 93, 146601 (2004). $^{3}$A. Kormanyos, Phys. Rev. B 82, 155316 (2010). $^{4}$A. M. Gilbertson, et al., Phys. Rev. B 79, 235333 (2009).