Magnetic Properties and GMR of Sputtered Permalloy/Au Multilayers

We report on structural, magnetic, and GMR properties of permalloy/Au multilayers where permalloy = Ni$\text{}_{83}$Fe$\text{}_{17}$, deposited by face-to-face sputtering onto Si(111) substrate. X-ray diffraction studies confirmed a good structural quality of our multilayers. The samples were characterised with vibrating sample magnetometer, longitudinal magnetooptical Kerr effect and giant magnetoresistance measurements. It was determined that our multilayers are magnetically very soft with H$\text{}_{c}$ ≈ 1 Oe and show uniaxial anisotropy with H$\text{}_{K}$ ≈ 5 Oe. For gold sublayer thickness d$\text{}_{Au}$ close to 1.1 nm the antiferromagnetic coupling is present in very narrow Au thickness range (≈ 0.2 nm). Despite a good structural quality of samples relatively small giant magnetoresistance value (1.2% at room temperature) was found. It is due to non-perfect aniferromagnetic coupling caused by pinholes.