On the effectiveness of magnetotactic bacteria for visualizations of magnetic domains

• Published in: Journal of magnetism and magnetic materials 1994-05, Vol.133 (1), p.409-412
• Main Authors: Harasko, G., Pfützner, H., Futschik, K.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Domain effects, magnetization curves, and hysteresis; Domain walls and domain structure; Exact sciences and technology; Magnetic properties and materials; Physics
• ISSN: 0304-8853
• DOI: 10.1016/0304-8853(94)90580-0

In an earlier paper we demonstrated that magnetotactic bacteria (MB) can be applied for nondestructive visualizations of domain structures in soft magnetic materials. In comparison with colloid techniques, this method shows a much higher sensitivity due to a different contrast mechanism. The present paper discusses limits of practical application of this technique regarding the possible resolution of narrow domains and supplementary domains respectively. Due to Brownian motion of the cells on SiFe a visualization is in principle restricted to domains of width d > 60 μm as well as to main domains. Experiments and an analysis of the contrast mechanism in connection with results of computer simulations of the spatio-temporal MB distribution indicate that stray fields of amorphous soft magnetic materials are too weak to allow a resolution of their narrow surface structure by means of motile MB. However, it can be visualized by means of MB with lost motility.