Study of magnetic interface and its effect in Fe/NiFe bilayers of alternating order

TL;DR

This study investigates how the order of magnetic layers in Fe/NiFe bilayers affects magnetic properties, revealing that layer order significantly influences interfacial coupling, magnetic parameters, and microstructure, with minimal impact on damping.

Contribution

It provides new insights into how alternating the order of magnetic layers modifies interfacial exchange coupling and magnetic parameters in Fe/NiFe bilayers.

Findings

Interfacial exchange coupling varies with layer order.

Magnetic parameters like coercivity and anisotropy nearly double when NiFe is grown over Fe.

Interfacial magnetic moment increases by 18% with different layer order.

Abstract

We present a comprehensive study on the magnetization reversal in Fe/NiFe bilayer system by alternating the order of the magnetic layers. All the samples show growth-induced uniaxial magnetic anisotropy due to oblique angle deposition technique. Strong interfacial exchange coupling between the Fe and NiFe layers leads to the single-phase hysteresis loops in the bilayer system. The strength of coupling being dependent on the interface changes upon alternating the order of magnetic layers. The magnetic parameters such as coercivity HC, and anisotropy field HK become almost doubled when NiFe layer is grown over the Fe layers. This enhancement in the magnetic parameters is primarily dependent on the increase of the thickness and magnetic moment of Fe-NiFe interfacial layer as revealed from the polarized neutron reectivity (PNR) data of the bilayer samples. The difference in the thickness and magnetization of the Fe-NiFe interfacial layer indicates the modification of the microstructure by alternating the order of the magnetic layers of the bilayers. The interfacial magnetic moment increased by almost 18 % when NiFe layer is grown over the Fe layer. In spite of the different values of anisotropy fields and modified interfacial exchange coupling, the Gilbert damping constant values of the ferromagnetic bilayers remain similar to single NiFe layer.