Direct Observation of Magnetic Gradient in Co/Pd Pressure-Graded Media

TL;DR

This study uses magnetometry and neutron scattering to analyze how pressure grading during sputtering affects the magnetic depth profile of Co/Pd multilayers, revealing significant magnetization variation and exchange coupling effects.

Contribution

It provides direct experimental evidence of magnetic property variation in pressure-graded Co/Pd multilayers using polarized neutron reflectometry.

Findings

Magnetization varies significantly across pressure-graded regions.

Higher deposition pressure decreases saturation magnetization.

Pressure grading increases coercivity and maintains exchange coupling.

Abstract

Magnetometry and neutron scattering have been used to study the magnetic properties of pressure graded Co/Pd multilayers. The grading of the multilayer structure was done by varying the deposition pressure during sputtering of the samples. Magnetic depth profiling by polarized neutron reflectometry directly shows that for pressure-graded samples, the magnetization changes significantly from one pressure region to the next, while control samples sputtered at uniform pressure exhibit essentially uniform magnetic depth profiles. Complementary magnetometry results suggest that the observed graded magnetic profiles are due in part to a decrease in saturation magnetization for regions deposited at progressively higher pressure. Increased deposition pressure is shown to increase coercivity, and for graded samples, the absence of discrete steps in the hysteresis loops implies exchange coupling among regions deposited at different pressures.