Cyclotron resonance in indium. Electron-phonon effects

Abstract

The electron-phonon interaction strength depends upon the distance of the quasiparticle from the Fermi level. Thus the cyclotron mass and the electronic lifetime vary with the temperature T and the microwave frequency Omega . An experimental study in the range 1.5-5 K, 73-460 GHz is reported, of these dependences for one orbit in indium. The mass m* increases according to the T² ln (T₀/T) and Omega ² ln ( Omega ₀/ Omega ) laws. The maximum changes observed are m* (5K)/m* (1.5K)=1.02 and m* (460 GHz)/m* (136 GHz)=1.01. These observed variations can be predicted easily from the Eliashberg function alpha ²F( omega ) experimentally obtained by tunnelling techniques. The relaxation frequency tau ^-1(T) can vary more rapidly than T³. This nonclassical law is attributed to the appearance of a new diffusion process at finite frequency.