By Topic

Optical trapping and manipulation of magnetic holes dispersed in a magnetic fluid

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$31 $31
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

8 Author(s)
Sun, Ting ; Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, Guangdong 510006, People’s Republic of China ; Fu, Zhi-Cheng ; Zhao, Wei-Ren ; Deng, Hai-Dong
more authors

Your organization might have access to this article on the publisher's site. To check, click on this link:http://dx.doi.org/+10.1063/1.3386522 

The optical trapping and manipulation of magnetic holes (MHs) dispersed in a magnetic fluid is systematically investigated. It is found that the gradient force, which tends to attract MHs to the beam center, can be completely counteracted by the repulsive force between MHs induced by a magnetic field. As a result, a depletion region is created at the laser beam spot for a sufficiently strong magnetic field. This phenomenon can be easily observed for large MHs with a diameter of 11 μm. However, it does not appear for MHs with a smaller diameter of 4.3 μm. It is revealed that the enhancement in the concentration of magnetic nanoparticles in the laser spot region as well as the clustering of these nanoparticles leads to a much stronger interaction between MHs when a magnetic field is applied. Consequently, the magnetic field strength necessary to create the depletion region is significantly reduced. We also find that the trapping behavior of MHs depends strongly on the thickness of the sample cells. For thin sample cells in which only one layer (or a two-dimensional distribution) of MHs is allowed, we can observe the creation of depletion region. In sharp contrast, MHs can be stably trapped at the center of the laser beam in thick sample cells even if a strong magnetic field is imposed. This phenomenon can be explained by the existence of a gradient in magnetic field strength along the direction perpendicular to the sample cells. Apart from individual MHs, we also investigate the movement of MH chains under the scattering force of the laser beam. It is observed that MH chains always move along the direction parallel to the magnetic field. This behavior can be easily understood when the anisotropy in viscosity caused by the applied magnetic field is considered.

Published in:

Journal of Applied Physics  (Volume:107 ,  Issue: 9 )