  The giant spin Hall effect in magnetic heterostructures along with low spin
memory loss and high interfacial spin mixing conductance are prerequisites to
realize energy efficient spin torque based logic devices. We report giant spin
Hall angle (SHA) of 28.67 (5.09) for W (Ta) interfaced epi- Co60Fe40/TiN
structures. The spin-orbit torque switching current density (J_Crit) is as low
as 1.82 (8.21) MA/cm2 in W (Ta)/Co60Fe40(t_CoFe)/TiN structures whose origin
lies in the epitaxial interfaces. These structures also exhibit very low spin
memory loss and high spin mixing conductance. These extraordinary values of SHA
and therefore ultra-low J_Crit in semiconducting industry compatible epitaxial
materials combinations open up a new direction for the realization of energy
efficient spin logic devices by utilizing epitaxial interfaces.
