The Magnetic Properties of [Co/Pt] Superlattices

Abstract

Magnetic materials with perpendicular magnetic anisotropy (PMA) are applicable to spintronic devices such as spin-transfer torque (STT) devices. The STT devices demand two important elements: thermal stability and low switching current density [1]. It is well known that the thermal stability and the low switching current density need certain PMA energy. In this study, we investigate the magnetic properties of the Si substrate/Ta(4 nm)/Pt(4 nm)/[Co(0.5-1.5 nm)/Pt(1.1 nm)]3/Ru(4 nm) structure fabricated by using a magnetron sputtering system. After film deposition, the samples were annealed at 300 oC, 1hour. The systematic polar magneto-optic Kerr effect measurements are performed for t he fabricated sample to investigate magnetic properties. We find that the coercive field (Hc) increases with increasing Co thickness up to 0.9 nm. And then, the Hc decreases with increasing Co thickness. Also, we fabricate the Si substrate/Ta(4 nm)/Pt(4 nm)/[Co(0.8 nm)/Pt(0.5-1.5 nm)]3/Ru(4 nm) structure by using a magnetron sputtering system to investigate the effect of Pt layer.