Photoabsorptive magnetic instability of magnetic liquid under uniform heating by laser

A. Cebers^1,2 - T. Du¹ - W. Luo¹

¹ Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
² Institute of Physics, Latvian Academy of Sciences, Salaspils-1, LV-2169, Latvia

Abstract
Mechanism of the new instability connected with arising magnetic field gradients under nonuniform heating by the light absorption in the external field is found. The physical picture of the instability allows to explain the results of several experimen-tal observations where the formation of the big agglomerates of the magnetic parti-cles has been observed only at simultaneous action of the illumination by light and magnetic field. Critical magnetic field dependencies on the thickness of the layer and power of the laser have been found which are in fair agreement with the experimen-tal values for the critical magnetic field strength when time dependent phenomena for the thermal lens effect in magnetic fluid films between two solid walls occur. Extension of the approach proposed in the present work to realistic cases of the heating by Gaussian laser beams is possible and is connected with the consideration of 2D Schredinger equation and eigenvalue problem of some integro-differential operator. Figs. 3, refs. 11.