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Domain structure and force analysis of micro-magnetic patterns for bio-functionalized bead actuation

Domain structure and force analysis of micro-magnetic patterns for bio-functionalized bead actuation
Alternative Title
세포 운반 비드의 힘 분석과 마이크로 패턴의 자구 모양 관측
Jung, Eun Joo
DGIST Authors
Jung, Eun JooKim, Cheol GiJang, Jae Eun
Kim, Cheol Gi
Jang, Jae Eun
Issued Date
Awarded Date
Magnetic domainX-ray microscopyPhase-locked anglePhase-slipping anglePhase-lockedPhase-slippingMaxwell 시뮬레이션자구X-ray 마이크로스코프OOMMF
One of the important items for the determination of the macroscopic behavior of the thin magnetic film is the arrangement of magnetic domains as a function of an applied external field. These domain structures of the magnetic thin films are observed by the Magnetic transmission x-ray microscopy. The magnetic transmission x-ray microscopy is a novel technique to image element specifically magnetic domain structures. As the element-specific magnetic contrast which is due to x-ray magnetic circular dichroism scales with the projection of the magnetization onto the photon propagation direction both out-of-plane and in-plane magnetic domain structures can be studied. While observing the domain structures, enhance magnetic contrast and eliminates non-magnetic background so that, each image was normalized to a reference image taken at saturation state. Using magnetic transmission x-ray microscopy, we characterized the domain structure of the magnetic patterns including half disk and full disk and observed the vortex state of the magnetic pattern in demagnetized state. The change in vortex state for the magnetic patterns by changing the applied filed is also measured by x-ray microscopy. Furthermore, the demagnetized states for the full disk micro-magnet were determined by OOMMF simulation which is good agreement with the magnetic domain structure measured by X-ray microscopy.
In addition, the non-linear dynamics of superparamagnetic beads moving around the periphery of patterned magnetic disks in the presence of an in-plane rotating magnetic field was studied here. Two different dynamical regimes are observed in experiments, including (1) phase-locked motion at maximum driving frequencies, (2) phase-slipping motion above a first critical frequency fc1.
The force calculations, Phase-locked and Phase-slipping angles are calculated by the superparamagnetic bead around a disk micro-magnet under an applied in-plane rotating field in clockwise direction. Due to the magnetic field gradient produced by the micro-magnets, the beads can be trapped at the location of high induced field. Under the rotating field, there could be a phase lag of bead from the field direction, and the schematics for governing forces on a moving bead are discussed. ⓒ 2016 DGIST
Table Of Contents
Ⅰ. Introduction 1 --
Ⅱ. Theoretical background 4 --
2.1. Magnetic anisotropy 4 --
2.1.1. Magnetocrystalline Anisotropy 4 --
2.1.2. Stress Anisotropy 8 --
2.1.3. Shape Anisotropy 9 --
2.1.4. Induced magnetic anisotropy 12 --
2.2. Magnetic domain 13 --
2.3. Micromagnetic simulation (OOMMF) 20 --
2.4. Magnetic force simulation (Ansys, Maxwell) 23 --
Ⅲ. Experiment 25 --
3.1. Fabrication of pattern 25 --
3.1.1. Photolithography 25 -- Photolithography process 25 -- Photoresist 26 -- Mask aligner 26 --
3.1.2. Electron beam lithography 28 -- Electron beam lithography process 28 --
3.1.3. Sputtering 30 -- Diode sputtering 30 -- Magnetron sputtering 31 --
3.2. Domain Measurement 32 --
3.2.1. X-ray microscopy 32 --
3.3. Magnetic actuation 34 --
3.4. Magnetic beads characterization and conjugation of Atto-520 biotin 36 --
Ⅳ. Result & Discussion 38 --
4.1. Magnetic Domain 38 --
4.2. Force calculation and phase lag of magnetic beads 41 --
4.3. Method of magnetic field calculation and beads actuation 45 --
Ⅴ. Conclusion 49 --
References 51 --
Summary 55
Emerging materials Science
Related Researcher
  • 김철기 Kim, CheolGi 화학물리학과
  • Research Interests Magnetic Materials and Spintronics; Converging Technology of Nanomaterials and Biomaterials; Bio-NEMS;MEMS
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Department of Physics and Chemistry Theses Master


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