Polymer Micelle Directed Magnetic Cargo Assemblies Towards Spin‐wave Manipulation

Abstract

Spin‐wave based technologies that use collective oscillation of electrons termed magnons have been proposed for future computing landscapes due to their low energy consumption and high data transfer speeds. Magnonic crystals, materials with magnetic properties periodically varied in space, are central to such technologies. However, they are currently limited by the lithography techniques used for the magnetic patterning. To address this issue, bottom‐up self‐assembly using polymer templates to order magnetic cargo is presented. In this work, block copolymer micelles are used as templates to direct the organization of polyoxometalate (POM) molecules into organized assemblies. The structural organization of these assemblies is evaluated using microscopy and scattering techniques. The organized POM assemblies are demonstrated to modulate spin‐waves excited in permalloy thin films. This work demonstrates the first use of a bottom‐up approach to realize the fabrication of a magnonic assembly at the nanoscale. It further paves the way to achieve magnon‐mediated self‐assembled computing architectures.

Geometric Frustration and Long-Range Ordering Induced by Surface Pressure Oscillation in a Langmuir–Blodgett Monolayer of Magnetic Soft Spheres

“…As noted in the Introduction, the air–water interface is not a system confined by hard boundaries and so falls between a 2-D and 3-D system. In such a system, dependent on the energetics of interaction with the solvent, the energy may be minimized by buckling of the layer, giving rise to the observed square packing, as also seen in similar systems differently prepared. ,, …”

“…Polyoxometalate salt [K 20 [(W)­W 5 O 21 (SO 4 )] 12 (VO) 30 (SO 4 )­(H 2 O) 63 ] 18‑ , in which the anion is represented as [V 30 W 72 ] 18‑ , was prepared by literature methods. , The POM has a net magnetic moment at room temperature of 14.02 μ B , which we determined by NMR spectroscopy using the Evans method . The surfactant-encapsulated dimethyl-dioctadecylammonium salt [DODA] 18 [V 30 W 72 ] was prepared by treating an aqueous solution of the POM cluster [V 30 W 72 ] 18‑ with a stoichiometric quantity (1:18) in chloroform solution of the surfactant dimethyl-dioctadecylammonium bromide (C 38 H 80 BrN, [DODA] + Br – ) followed by constant stirring for 30 min.…”

“…The study of magnetism in 2-dimensional structures is of particular interest for the field of “magnonics”: logic elements that exploit magnetic spin waves as an approach to overcome the limitations imposed on conventional electronics by power dissipation . While magnonic elements are conventionally fabricated by “top-down” methods of lithography, deposition, and etching, there is interest to explore “bottom-up” methods that might provide smaller-scale structures and hence higher switching frequencies. ,, One such possible method is the Langmuir–Blodgett (L-B) deposition of 2-D layers of surfactant encapsulated magnetic clusters. Surfactant-encapsulated polyoxometalate clusters , (POMs) are of particular interest in this regard.…”

“…Polyoxometalates have been identified as candidates that can serve as building blocks in the fabrication of molecular devices, ,− and magnetic polyoxometalates are candidates for magnonic devices . Integration as thin films remains a challenge.…”

“…1 While magnonic elements are conventionally fabricated by "top-down" methods of lithography, deposition, and etching, there is interest to explore "bottom-up" methods 2 that might provide smaller-scale structures and hence higher switching frequencies. 1,3,4 One such possible method is the Langmuir−Blodgett (L-B) deposition 2 of 2-D layers of surfactant encapsulated magnetic clusters. Surfactant-encapsulated polyoxometalate clusters 5,6 (POMs) are of particular interest in this regard.…”