The role of chemical and microstructural inhomogeneities on interface magnetism

Abstract

The study of interfacing effects arising when different magnetic phases are in close contact has led to the discovery of novel physical properties and the development of innovative technological applications of nanostructured magnetic materials. Chemical and microstructural inhomogeneities at the interfacial region, driven by interdiffusion processes, chemical reactions and interface roughness may significantly affect the final properties of a material and, if suitably controlled, may represent an additional tool to finely tune the overall physical properties. The activity at the Nanostructured Magnetic Materials Laboratory (nM2-Lab) at CNR-ISM of Italy is aimed at designing and investigating nanoscale-engineered magnetic materials, where the overall magnetic properties are dominated by the interface exchange coupling. In this review, some examples of recent studies where the chemical and microstructural properties are critical in determining the overall magnetic properties in core/shell nanoparticles, nanocomposites and multilayer heterostructures are presented.

The noncollinear interlayer coupling in NiFe/NiO/NiFe trilayers

“…Due to the difficulty in directly characterizing the AFM spin structures, there are still controversies in understanding the mechanism of noncollinear IEC across AFMI layer [18,19,21]. Additionally, while interface mixing is commonly observed in FM/AFMI heterostructures [22][23][24][25][26][27], which can modify the nearest-neighbor exchange across the interface [28,29], its impacts on the IEC are seldom reported. Although the origin and modifications of the noncollinear IEC is still under intense research, its applications in sensors and spintronic devices deserve attention.…”

Interfacial Mixing Effect in a Promising Skyrmionic Material: Ferrimagnetic Mn$_4$N

“…Furthermore, it has been reported that in many of these heterostructures, interfacial mixing and dead layers exist at the interfaces of magnetic and non-magnetic layers. Such interfacial compositional heterogeneities have led to varying magnetic properties, such as thickness-dependent anisotropy and magnetization [15][16][17][18][19][20][21] . These present challenges in fabricating and developing devices with magnetic thin films, such as magnetic tunnel junctions 22 .…”

Magnetism of Nanoparticles: Effect of the Organic Coating

“…The surface [ 25 , 26 ] contribution can be controlled through the interaction with another phase in contact with it, i.e., exploiting the interface effect, which can be of different type depending on the nanoparticle system and the nature of the two phases in contact [ 27 ]. As an example, in bimagnetic core/shell particles, combining ferromagnetic and antiferromagnetic phases, the exchange coupling at the interface between the core and the surface shell can give rise to the exchange bias phenomenon [ 28 , 29 ], which is often accompanied by an increase of anisotropy, due to the so-called “exchange anisotropy”.…”