Optical Properties of Fe₃O₄ Magnetic Fluid from Iron Sand

Nowadays, a high sensitive sensor for the magnetic field has become an essential tool that vastly desired in several fields, especially in biomedical application. Therefore, the development of preparing material for the magnetic sensor becomes crucial to be conducted. In this experimnet, we propose the use of Fe₃O₄ magnetic fluid prepared from a local iron sand in Indonesia as a material for a magnetic sensor. In this work, optical activities of the Fe₃O₄ magnetic fluid as the effect of magneto-optics were performed under varying external magnetic field. The polarization direction change of the laser was detected as a function of the external magnetic field with the exponential function. Moreover, the intensity collected by a photodetector exhibited a linear correlation with the external magnetic field. These phenomena become strong evidence that the prepared Fe₃O₄ magnetic fluid opens potential to be applicated further as sensors, especially as a high sensitive optics-based sensor for the magnetic field.