Magnetic Field Modulation Method for Measurements of Magnetophonon Effect

Abstract

The first and the second derivatives of the transverse magnetoresistance are measured by the magnetic field modulation technique and are compared with each other. The results show that the second derivative is easily affected by the second harmonic component of the modulation magnetic field and that the peaks of the second derivative at high magnetic fields will not give accurate resonance positions. To avoid such effect and to measure the magnetophonon effect accurately, the first derivative method of the magnetoresistance is proposed for the magnetophonon measurements as the best method. It is also shown that the oscillatory component of the magnetophonon resonance can be obtained by numerical integration of the first derivative signals. The effective mass of the conduction band edge is estimated to be 0.0664±0.0005m for n-GaAs at 160 K and 0.0135±0.0002m for n-InSb at 77 K.