Magnetism and interactions at the nanoscale: synthesis, characterization and applications

Magnetic nanomaterials play a pivotal role in both fundamental research and a wide range of technological applications. This dissertation delves into the world of nanomagnetism, exploring various aspects of magnetic iron cobalt (Fe65Co35) structures in the form of nanocubes and nanochains. The research employs advanced techniques such as Quantum Design DynaCool Physical Property Measurement System (PPMS), vibrating sample magnetometer (VSM), and magnetic force microscopy (MFM) to provide insights into nanomagnetic properties. The first part of the research investigates Fe65Co35 nanocubes of different sizes, ranging from 10 to 100 nm. A finite element micromagnetic model is used to predict the magnetic behavior. The study uncovers size-dependent magnetization configurations and verifies these findings through experimental synthesis, highlighting how particle size influences spin configurations in Fe65Co35 nanocubes. The second segment introduces a novel one-step synthesis strategy for magnetic nanochains, eliminating the need for an external magnetic field. It explores the influence of precursor concentration on the automatic alignment of nanocubes into nanochains. The research combines COMSOL simulations and fluid dynamics calculations to elucidate the forces at play. It reveals that the assembly mode of nanocubes depends on their sizes, leading to a comprehensive understanding of their behavior. In the third part, the study delves into dipolar interactions within nanoparticles and self-assembled nanochains. The research explores how external magnetic fields influence the alignment of these nanostructures and their collective magnetic properties. It identifies a threshold concentration for the transition from ferromagnetic to antiferromagnetic coupling in nanochains, which influences their magnetic behavior and potential applications in soft magnetic actuators. The study successfully constructs a reconfigurable magnetic composite film and demonstrates the creation of magnetic soft actuators with various actuation modes. In addition to experimental work, numerical simulations are developed to predict local tangent angles and explore the relationship between nanoparticle density, arrangement, and superstructure dimensionality. These simulations closely align with experimental findings, providing insights into the structural properties of the systems. This research enhances our comprehension of the structure-property relationships in magnetic nanostructures, opening up possibilities for tailored dimensional order and improved magnetic properties within multidimensional magnetic nanostructures.

Name thesis:degree_name

Ph. D., Materials Science and Engineering

Level thesis:degree_level

Doctor of Philosophy

Discipline thesis:degree_discipline

Materials Science and Engineering

Grantor

Cornell University

Year dc:date.issued

2024

Author dc:creator

• Chen, Yulan

Committee members dc:contributor.committeemember

• Robinson, Richard
• Fuchs, Gregory

• Actuators
• Magnetic composites
• Magnetic nanochains
• Magnetic nanoparticles
• Self-assembly
• Soft magentic

Statement dc:rights

• Attribution 4.0 International

Licence dc:rights.uri

• https://creativecommons.org/licenses/by/4.0/

Language dc:language.iso

en

DOI

https://doi.org/10.7298/b31g-zd86

Dc Identifier Other

ProQuest Submission ID: 14377
ProQuest Publication ID: 31331948

OAI identifier oai:identifier

oai:ecommons.cornell.edu:1813/116412