  We present measurements of spin orbit torques generated by Ir as a function
of film thickness in sputtered Ir/CoFeB and Ir/Co samples. We find that Ir
provides a damping-like component of spin orbit torque with a maximum spin
torque conductivity 1.4e5 in SI unit and a maximum spin-torque efficiency of
0.04, which is sufficient to drive switching in an 0.8 nm film of CoFeB with
perpendicular magnetic anisotropy. We also observe a surprisingly large field
like spin orbit torque. Measurements as a function of Ir thickness indicate a
substantial contribution to the FLT from an interface mechanism so that in the
ultrathin limit there is a non-zero FLT with a maximum torque conductivity
-5.0E4 in the SI unit. When the Ir film thickness becomes comparable to or
greater than its spin diffusion length, 1.6 nm, there is also a smaller bulk
contribution to the fieldlike torque.
