Study of the Magneto-optical Ellipsometry
|Keywords||Magneto-optical ellipometry ultra-thin magnetic film magneto-optical properties|
Now the magneto-optical materials and devices are essential to modern communications, aerospace, radar, medical. Based on ellipometry technique and magneto-optical effect, Magneto-optical ellipometry can measured the optical constants and magnetic constants of magnetic materials. It has been widely applied in characterizing the magnetic properties of ultra-thin film and multilayer. Magneto-optical ellipometry, the necessary detection tools to guide the growth of thin film, can provide accurate information for the different stages of film growth and carry out in situ measurements; it can provide a reliable theoretical and experimental basis for the optimization and upgrading of the magneto-optical films; it can provide advanced measurement tools to find new magneto-optical storage materials.This thesis gives a systematic review of the developments of magneto-optical ellipsometry, also analyze the application of ellipsomentry and the measurement of surface magneto-optical Kerr effect. Moreover, the magneto-optical ellipsometry is successfully built by the analysis of theory and experiment of the magneto-optical ellipsometry. The magneto-optical properties of the permalloy and ultra-thin Fe film are obtained by using the magneto-optical ellipsometry. The result shows that the magneto-optical ellipsometry is suitable for study of the magneto-optical properties of a single atomic layer. The magneto-optical Kerr effect of the bulk and multilayer structure are theoretical analyzed, and a larger Kerr rotation angle is obtained through the experiments and computer simulation of the overlayer material. The main initiative contributions in this thesis include following aspects:(1) The magneto-optical ellipsometry reduces the demand of the accuracy of the laser by introduce the chopper and lock-in amplifier to this platform. And the cost of measurement is significant saved using the semiconductor laser instead of original polarized laser. The detector will receive a pulsed laser instead of continuous laser by setting the frequency of the choppers modulation. And the chopper can emit the square wave with the same frequency as the reference signal of the lock-in amplifier. A series of computer simulations and experiments have shown of the reliability and accuracy of Magneto-optical ellipometry.(2) The relationship between the complex refractive index of the overlayer and the magneto-optical Kerr rotation angle is proposed. The magneto-optical Kerr rotation angle will increase with the addition of the refractive index n of the overlayer, and with the decrease of the extinction coefficient k at the same thickness of the overlayer. And then a simulation was made with the samples which have different overlayers of Al、Au、Cu、Ag、Ta to find the best overlayer material.