Observation and modeling of ordered structures of magnetic fluid films under perpendicular magnetic fields

S. Y. Yang¹ - I. J. Yang¹ - H. E. Horng¹ - Chin-Yih Hong² - H. C. Yang³

¹ Department of Physics, National Taiwan Normal University, Taipei 117, Taiwan
² Department of Mechanical Engineering, Da-Yeh University, Chang-Hwa 515, Taiwan
³ Department of Physics, National Taiwan University, Taipei 106, Taiwan

Abstract
Structures of magnetic columns were observed to investigate the interaction of the magnetic columns under magnetic fields. The magnetic columns show an ordered hexagonal pattern in the magnetic fluid film under perpendicular magnetic fields H with various sweep rates dH/dt. At a fixed sweep rate, the distance between two neighboring columns was found to decrease with increasing H. Interactions among the magnetic cloumns were considered to establish the correlation between the column distance d and the applied magnetic field H. By combining the experimental data with the theoretical results, it was found that the dipole interactions govern the d-H behavior in the region where thermal energy is negligible. In addition, the finite size of the magnetic columns plays a role in the dipole interaction. Table 1, Figs 4, Refs 15.