Effect of Modified Periodic Waveforms on Current-Induced Spin Polarization Measurements

Applying a time-varying periodic voltage to a semiconductor sample generates a current-induced electron spin polarization (CISP). Using an ultrafast mode-locked laser and lock-in detection scheme, we measure CISP on a 500nm indium gallium arsenide epilayer (2.6% indium concentration) grown on a (001) gallium arsenide substrate via Faraday rotation and extract the spin generation rate. While the measured spin polarization initially increases linearly with electric field as observed in previous work, larger applied voltages lead to sample heating and a decreasing spin generation rate. We modify the applied voltage waveform to reduce heating, requiring that we add an extra data processing step to our measurement technique. We then recover the linear dependence of spin generation rate with electric field even at larger applied voltages. Future CISP studies can utilize this technique to investigate CISP under larger applied electric fields.