Noise Properties of the Faraday Effect Measurement Systems

Abstract

Nowadays, nanomagnetic devices have a main role in computer industries. To observe magnetic features of the nanomagnetic device, Magneto-optical effects such as Kerr effect and Faraday effect can be used. We report the fabrication of the Faraday effect measurement setup for characterization of nanomagnetic elements. With achievement of low noise measurement configuration by precision electronic measurements, Faraday effect was observed. The essence of the experiment is to measure a light intensity that is transmitted from the transparent magnetic material. Light intensity is measured by a photodiode detector (Hamamatsu S5870) which produced the laser-induced photocurrent. Using transimpedance amplifier, the signal is converted to the voltage which is measured by the lock in amplifier (Stanford Research SR810). By performing the measurement at different lock-in frequencies and different analyzer angles, we systematically analyzed various random noise sources and their effect to the signal to noise ratio. The interestingly, the noise characteristics of the measured photocurrent exhibit a 1/f noise behavior with a scaling exponent practically 1.