Study of [Co/Ni]_N/ [Co/Pt]_N-based spin valves with perpendicular magnetic anisotropy

Abstract

A structure of Pt/ [Co/Ni]₂/Au/ [Co/Pt]_N with perpendicular magnetic anisotropy was prepared successfully by magnetron sputtering technique. The magnetic properties dependence of Au thicknesses and [Co/Pt] layer repetition number have been studied. The results show that when the [Co/Pt] layer repetition number is 4, the strongest coupling among the samples occurs when the Au layer is 3 nm for its largest Hall voltage and large switching field plateau. The Hall loop of the sample has obvious perpendicular magnetic anisotropy. The magnetoresistance of Pt/ [Co/Ni]₂/Au(t)/ [Co/Pt]₄ has vibration behaviour due to the Ruderman-Kittel-Kasuya-Yosida interaction with the increase of t_Au. As the thickness of the Au spacer is determined to be 3 nm, the study of dependence of [Co/Pt] layer repetition number to the magnetic properties shows that the N has significant influence to the magnetoresistance of the multilayer films. When N is 5, the MR of the sample has the maximum value and the optimum sample is structured as Pt(4)/[Co(0.2)/Ni(0.4)]₂/Co(0.2)/Au(3)/[Co(0.4)/Pt(2.0)]₅/Pt(0.5) (unit:nm). It has obvious perpendicular magnetic anisotropy features and large switching field plateau and the integration with device can be studied furtherly.

Keywords:

• Spin valves
• perpendicular magnetic anisotropy
• magnetoresistance
• anomalous Hall effect

Funding

Work supported by National Natural Science Foundation of China (Grant No. 11174020, 51271211) and Characteristic research team of Beijing Technology and Business University (Grant No. 19008001076)