Exploring the magnetization dynamics of NiFe/Pt multilayers in flexible substrates

M.A Corrêa,R Dutra,T.L Marcondes,T.J.A Mori,F Bohn,R.L Sommer

doi:10.1016/j.mseb.2016.06.008

Abstract

We investigate the structural and magnetic properties, and the magnetization dynamics in Ni81Fe19/Pt multilayer systems grown onto rigid and flexible substrates. The structural characterization shows evidence of a superlattice behavior, while the quasi-static magnetization characterization reveal a weak magnetic anisotropy induced in the multilayers. The magnetization dynamics is investigated through the magnetoimpedance effect. We employ a theoretical approach to describe the experimental magnetoimpedance effect and verify the influence of the effective damping parameter on the magnetization dynamics. Experimental data and theoretical results are in agreement and suggest that the multilayers present high effective damping parameter. Moreover, our experiments raise an interesting issue on the possibility of achieving considerable MI% values, even for systems with weak magnetic anisotropy and high damping parameter grown onto flexible substrates.

Highlights

IntroductionThe magnetization dynamics in ferromagnetic multilayers consisting of a ferromagnetic/metallic nonmagnetic (FM/NM) structure has attracted increasing interest due to the wide potential of application in current and emerging technologies, as well as due to the importance of the understanding in terms of fundamental physics of a richness of phenomena observed in these systems with reduced dimensions [1,2,3,4,5,6,7]
In the recent decades, the magnetization dynamics in ferromagnetic multilayers consisting of a ferromagnetic/metallic nonmagnetic (FM/NM) structure has attracted increasing interest due to the wide potential of application in current and emerging technologies, as well as due to the importance of the understanding in terms of fundamental physics of a richness of phenomena observed in these systems with reduced dimensions [1,2,3,4,5,6,7].Electrical and magnetic properties of the non-magnetic and ferromagnetic layers strongly affect the dynamic magnetic response of a multilayer [8,9]
Ruiz-Calaforra et al [12] presented a meticulous research on FM/NM multilayers, where FM is a ferromagnetic material, as NiFe and CoFeB, alloys commonly used as free layer in Tunnel Magnetoresistance (TMR) and Giant Magnetostriction (GMS) stacks, while NM is a non-magnetic spacer material, as Pt, Al, Cr, Ru and MgO, materials frequently employed in spintronics studies, and explored the magnetization dynamics through the ferromagnetic resonance effect (FMR) and inverse spin Hall effect

Summary

Introduction

The magnetization dynamics in ferromagnetic multilayers consisting of a ferromagnetic/metallic nonmagnetic (FM/NM) structure has attracted increasing interest due to the wide potential of application in current and emerging technologies, as well as due to the importance of the understanding in terms of fundamental physics of a richness of phenomena observed in these systems with reduced dimensions [1,2,3,4,5,6,7]. Ruiz-Calaforra et al [12] presented a meticulous research on FM/NM multilayers, where FM is a ferromagnetic material, as NiFe and CoFeB, alloys commonly used as free layer in Tunnel Magnetoresistance (TMR) and Giant Magnetostriction (GMS) stacks, while NM is a non-magnetic spacer material, as Pt, Al, Cr, Ru and MgO, materials frequently employed in spintronics studies, and explored the magnetization dynamics through the ferromagnetic resonance effect (FMR) and inverse spin Hall effect. From a strict analysis of dynamics properties when the external magnetic field is applied in longitudinal and transversal to the main axis of the wire, an estimative of aeff is provided. For this bilayer wire, aeff % 0:0083 [5], a lower value noticeably close to the usually verified for ordinary ferromagnetic NiFe thin films.

Experiment

Results and discussion

Conclusion