Polarized neutron reflectometry of magnetic nanostructures

• Published in: Physics of metals and metallography Vol. 116; no. 13; pp. 1337 - 1375
• Main Author: Toperverg, B. P.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.12.2015; Springer; Springer Nature B.V
• Subjects: Chemistry and Materials Science; Exchange; Grazing incidence; Magnetic properties; Magnetization; Materials Science; Mathematical analysis; Metallic Materials; Nanostructure; Reflectometry; Superconductors; Vectors (mathematics); Critical Edge; Scattering Length Density; Exchange Bias; Neutron Wave; Magnetic NANOSTRUCTURES
• ISSN: 0031-918X; 1555-6190
• DOI: 10.1134/S0031918X15130025

Among a number of methods employed to characterize various types of magnetic nano-structures Polarized Neutron Reflectometry (PNR) is shown to be a unique tool providing a scope of quantitative information on magnetization arrangement over relevant scales. Deeply penetrating into materials neutron spins are able to resolve vectorial profile of magnetic induction with accuracy of a fraction of Oersted over a fraction of nano-meters. This property is exploited in measurements of specular PNR which hence constitutes the method of depth resolved vector magnetometry widely used to examine magnetic states in exchange coupled magnetic superlattices, exchange bias systems, spin valves, exchange springs, superconducting/ferromagnetic heterostructure, etc. Off-specular polarized neutron scattering (OS-PNS) measures the in-plane magnetization distribution over scales from hundreds of nanoto hundreds of micrometers providing, in combination with specular PNR, access to lateral long range fluctuations of the magnetization vector and magnetic domains in these systems. OSPNS is especially useful in studies of co-operative magnetization reversal processes in various films and multilayers laterally patterned into periodic arrays of stripes, or islands of various dimentions, shapes, internal structures, etc., representing an interest for e.g. spintronics. Smaller sizes of 10?100 nm are accessed with the method of Polarized Neutrons Grazing Incidence Small Angle Scattering (PN-GISAS), which in a combination with specular PNR and OS-PNS is used to study self-assembling of magnetic nano-particles on flat surfaces, while Polarized Neutron Grazing Incidence Diffraction (PN-GID) complete the scope of magnetic information over wide range of scales in 3D space. The review of recent results obtained employing the methods listed above is preceded by the detailed theoretical consideration and exemplified by new developments addressing with PNR fast magnetic kinetics in nano-systems.