Paper Number
SC48 

Session
Suspensions and Colloids

Title
Alignment dynamics of magnetic microdisks in rotating magnetic field

Presentation Date and Time
October 15, 2015 (Thursday) 9:30

Track / Room
Track 1 / Constellation C

Authors (Click on name to view author profile)

1. Tan, Mingyang (Oregon State University, Chemical, Biological, and Environmental Engineering)
2. Song, Han (Oregon State University, Electrical Engineering and Computer Science)
3. Jander, Albrecht (Oregon State University, Electrical Engineering and Computer Science)
4. Dhagat, Pallavi (Oregon State University, Electrical Engineering and Computer Science)
5. Walker, Travis W. (Oregon State University, Chemical, Biological, and Environmental Engineering)

Author and Affiliation Lines (in printed abstract book)
Mingyang Tan¹, Han Song², Albrecht Jander², Pallavi Dhagat², and Travis W. Walker^1
1Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, OR 97331; ²Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331

Speaker / Presenter 
Tan, Mingyang

Text of Abstract
Next generation wireless communication devices require inductors and antennae to function at high frequencies. Composites with fine metallic magnetic particles embedded in a polymer matrix are promising materials for high-frequency application. Materials with magnetic anisotropy (i.e., rod-like or disk-shaped particles) are gaining increased attention, as they exhibit enhanced high-frequency permeability in comparison to materials with spherical particles. Moreover, magnetic alignment of these anisotropic particles further increases the high-frequency permeability and ferromagnetic resonance frequency. Alignment can be achieved by applying an external magnetic field, prior to freezing the configuration in the composite. In this study, we show that the application of a rotating magnetic field can bi-axially align disk-shaped particles, producing planar anisotropy in the composite. The dynamics of alignment are investigated, and the timescales associated with the alignment process as a function of the properties of the composite and the conditions of external magnetic field are studied. We introduce a theoretical Stokes-flow model to describe the dynamic process. This model guides the process control conditions to achieve highly aligned planar anisotropy. Experimentally, Ni and NiFe microdisks embedded within a composite are observed under bright-field optical microscopy. Comparisons between experiments and model time scales are made.