Interlayer exchange coupling across Cu/Ti/Cu spacer layer

The effect of introducing ultrathin Ti dopant layer on interlayer exchange coupling across spacer layer (S = Cu/Ti/Cu) was investigated in spin-valve (SV) structures. A sequence of SV with fixed Ti layers (t(Ti) = 0, 0.27, 0.54 nm) and variable thickness of Cu (0.6 less than or equal to t(Cu) less than or equal to 2.5 nm) was prepared using a sputtering technique. The values of the effective coupling energy (J) between ferromagnetic layers were determined from magnetization curves. The experimental J(t(S)) dependences (t(S) = 2t(Cu) + t(Ti)) determined for different t(Ti) show that the effective coupling is ferromagnetic with clearly seen traces of oscillatory coupling. From fitting procedure considering three types of interlayer coupling (oscillatory RKKY-like, magnetostatic and coupling due to pinholes) we conclude that introducing of ultrathin Ti dopant layer into Cu spacer results in increasing the period and decreasing the amplitude of RKKY term and has almost no effect on the magnetostatic coupling and ferromagnetic coupling due to pinholes.