Effects of Interlayer Coupling in Elongated $\hbox{Ni}_{80}\hbox{Fe}_{20}/\hbox{Au/Co}$ Nanorings

Abstract

We describe the magnetization reversal processes in multilayer elongated Ni 80 Fe 20 (10 nm) Au( = 0 to 20 nm) Co(20 nm) Si( 001) nanorings. For a field applied in-plane along the long axis, the hysteresis loops display a two-step switching for both = 0 nm and 2 nm, and a three-step switching for = 10 nm and 20 nm. Onion-to-vortex and vortex-to-reverse onion state transitions occur for a thin Au spacer due to strong exchange coupling between the layers. For a thick Au spacer layer, the Ni 80 Fe 20 layer switches first, then a two-step reversal of the Co, correlated with domain motion in the Ni 80 Fe 20 , occurs without the formation of vortex states as a result of magnetostatic interactions. There is a good agreement between the experimental results and micromagnetic simulations. Index Terms-Co Au Ni 80 Fe 20 , elongated nanorings, exchange coupling, MOKE.

Lithographically Patterned Electrodeposition of Gold, Silver, and Nickel Nanoring Arrays with Widely Tunable Near-Infrared Plasmonic Resonances

“…3,22,33,38 Lower energy resonances around 5000 cm À1 , similar to those observed in this work, have been demonstrated with larger diameter Ag and Au nanorings. 26,44 Although Ni nanorings are primarily studied for their magnetic or magneto-optic properties, 15,18 NIR plasmonic resonances have been observed for Ni nanodisks. 56 In this work, we observe a NIR plasmonic resonance from three different metal nanoring arrays, but note that nanoring array can be fabricated from many other metals and semiconductors with the LPNE approach.…”

“…Among the panoply of nanoscale objects that have been assembled into ordered arrays on surfaces, nanoscale toroidal rings or ″nanorings″ are increasingly popular structures that exhibit unique optical, electronic, and magnetic properties with a number of novel technological applications . Some examples include (i) gold or silver nanoring arrays that exhibit strong localized plasmonic resonances with applications in biosensors, − metamaterials, − and optical devices, , (ii) cobalt, iron, or nickel magnetic nanoring arrays that exhibit unique flux closure states with potential applications in magnetic storage, − and (iii) CdSe, InGaS, or GaN semiconductor nanorings that exhibit unique electronic states for optoelectronic devices. − A variety of theoretical approaches including Mie theory, plasmon hybridization, , Green’s tensor, and finite-difference time-domain (FDTD) numerical analysis have been used to calculate the electronic structure, plasmonic resonances, and local electromagnetic fields associated with nanorings. A key advantage of the nanorings is that their optical properties can be systematically tuned by varying the ring radius and thickness.…”

In Situ Study of ABC Triblock Terpolymer Self-Assembly under Solvent Vapor Annealing

“…Furthermore, this approach allows for observation of intermediate phases and order–order transitions during the annealing process. ,,, The self-assembly process of diblock copolymers has been extensively explored by real-time GISAXS studies, ,,,,, but there is limited work on the self-assembly of cyclic, branched, or multiblock polymer architectures, such as cyclic block copolymers, linear triblock terpolymers, ,,− miktoarm star terpolymers, ,, and bottlebrush copolymers. ,,, The phase behavior of multiblock polymers is more difficult to elucidate using ex situ characterization due to their additional degrees of freedom and a wider range of morphologies. These morphologies can offer additional functionality; for example, nanoscale ring structures formed from core–shell cylinders can exhibit desirable optical, electronic, and magnetic properties. ,− …”

Highly Ordered Nanoring Arrays Formed by Templated Si‐Containing Triblock Terpolymer Thin Films

“…The production of perfectly ordered objects at the nanometer scale is attracting considerable attention due to their enormous potential in creating surfaces with new functionalities. Among the panoply of nanoscale objects ordered into regular arrays, the nanoring is one of the most appealing structure to provide significant advancement in technological applications since it exhibits unique optical, electronic, and magnetic properties. For instance, due its two stable vortex states consisting of clockwise or counterclockwise circulations, the magnetic nanoring is an ideal candidate for magnetic random access memory (MRAM), where the direction of the rotating magnetic field of a ring‐shaped feature would correspond to digital data of either “0” or “1.” Therefore, the use of ultradense magnetic nanoscale ring arrays has been rapidly gaining interest for next‐generation MRAM.…”