Structures, Pd spacer polarization and magnetic properties of Co-Nb/Pd multilayers

Magnetic multilayers [Co-Nb(1.5 or 3.6 nm)/Pd(x nm)]40 were fabricated by radio frequency sputtering synthesis. The structures and magnetic properties of the Co-Nb/Pd multilayers were studied by x-ray diffraction, vibrating sample magnetometer, torque magnetometer and ferromagnetic resonance measurements. The oscillatory dependence of the phase structure, the strain, the ferromagnetic interlayer coupling and the spacer polarization of multilayers on the increase of Pd spacer thickness was observed. The relationship among phase structure, strain, interlayer coupling and the polarization of Pd spacers was discussed. The magnetic polarization of Pd spacers will enhance the ferromagnetic coupling between magnetic layers and will restrain antiferromagnetic coupling to occur. The spin-dependent electron transport along the normal direction of multilayers and its exchange interaction play key roles in causing these oscillatory behaviors.