Development Of Tunable High-speed Spin Noise Spectroscopy And Spin Noise Measurement Of N-GaAs

Spin noise spectroscopy is a frontier physical method of undisturbed measurement of spin dynamics.First spin noise spectroscopy experiment was realized after several decades of theory proposal,which was due to the long-term development of integrated circuits in accordance with Moore's law and the emergence of new computing architecture hardware.The physical content obtained by the measurement of the spin noise spectroscopy will in return promote the development of Moore's law and modern spin based electronic devices.We have done the systematic work from developing the spin noise spectrometer and the host computer software control platform,to using the developed instrument to measure a series of spin noise spectroscopy data of the n-GaAs sample,where we gain some physical conclusions.The paper includes the following two parts:(1)We demonstrated the necessity of using FPGA to develop the spin noise spectrometer and the superiority compared with traditional spectrum analyzer.We have purchased the appropriate hardware and carried out algorithm design,FPGA development,interface debugging,and the host computer software control platform development.Finally,we successfully developed the spin noise spectrometer which is in domestic leading position and Distinctive features of adjustment.(2)We used the developed spin noise spectrometer to measure the spin noise spectrum on the n-GaAs sample.First,we conducted the experiment for feasibility verification.We have successfully measured the spin signals using the spin noise spectrometer and verified the speed and flexibility of the developed instruments compared with the measurement results of the spectrometer.Results showed that our spin noise spectrometer was about 600 times faster than the commercial spectrometer.Then we have carried out a series of spin noise measurements that include magnetic field series,wavelength series,temperature series and power series on the n-GaAs sample and formed a completed measurement data.The wavelength series show that there is no essential difference in the electronic state of the ensemble measured from 832.1nm to 838.9nm wavelength range;The temperature series of different power shows that though the laser which is in the transparent wavelength range of Faraday effect does not excite the sample,the energy density of the detection light will still heat up the sample,and it will significantly reduce the spin life,especially at the temperature of the sample cavity below 20 K and the laser power above 1mW.This result instructs us that when we use the non-excitation measurement technique to measure the spin ensemble,The energy density of the probe laser should be strictly controlled to obtain the more intrinsic and accurate spin ensemble measurement results.