Versatile transmission ellipsometry to study linear ferrofluid magneto-optics

Field induced phase segregation in ferrofluids

“…In more theoretical treatments, the phase separation of the ferrofluid with initial concentration into two phases with lower and higher concentrations is generally described in terms of a "ferrocolloidal gas-ferrocolloidal liquid" phase transition. While performing experiments on the optical birefringence and dichroism of magnetite ferrofluids [30], we obtained some anomalous results, which could not be accounted for by established theories. More specifically, when the (nearly) homogeneous field was applied for long periods of time, typically more than 30 min, irreproducible intensity variations were often observed after switching off the magnetic field.…”

“…1. This setup is identical to the one used for the aforementioned magnetooptical studies [30] on diluted magnetite ferrofluids. In the gap between the poles of the magnet, we placed a thin-film glass cell (a standard Starna cuvette) with a 1 mm optical path length, filled with an oil-based magnetite (Fe 3 O 4 ) ferrofluid.…”

“…This effect is well-known and forms the basis of the anisotropic optical properties of ferrofluids subjected to an external field. Since the first discovery of magnetic birefringence and dichroism in these liquids [18,19], substantial research efforts have been focused on elucidating the origin of the magneto-optical properties and exploring their possible application as active optical devices, such as shutters, switches, polarizers and phase-changing elements [20][21][22][23][24][25][26][27][28][29][30].…”

Optical Properties of Fe3O4Magnetic Fluid from Iron Sand

“…Some reports in the literature show the occurrence of magneto-optic effect in the magnetic fluid [22,23]. The most important magneto-optic effect shown by the magnetic fluid is Faraday rotation, Faraday Ellipticity, Kerr Effect, linear dichroism, birefringence, and so forth [24]. Furthermore, it has been shown as well that Faraday rotation can happen in a railroad like-way.…”

Time dependent magnetically induced variations in optical transmission of magnetite nanoparticle aqueous suspension

“…The colloids of subdomain paramagnetic particles dispersed in a liquid carrier are termed ferrofluids. Ferrofluids exhibit a number of interesting magnetooptical phenomena including magnetically induced birefringence [7,8], magnetic dichroism [9], Faraday rotation and ellipticity [10]. Studies on optical limiting properties of SPION have also been reported [11].…”