HOT-ELECTRON TEMPERATURES OF 2-DIMENSIONAL ELECTRON GASES USING BOTH DEHAAS-SHUBNIKOV OSCILLATIONS AND THE ELECTRON-ELECTRON INTERACTION EFFECT

The experiments described in this paper were undertaken to investigate the possibility that cyclotron phonon emission plays a significant ro le in the energy-loss rate of hot electrons in the liquid-He-4 tempera ture range. Electron temperatures have been measured by the usual de H aas-Shubnikov method, and also by a technique based on the temperature dependence of the nonoscillatory magnetoresistivity, which is believe d to arise from the electron-electron interaction effect (EEI). Combin ing results from both methods should give a more or less continuous me asurement of electron temperature as a function of magnetic field; how ever, the method based on EEI is found to fail when omega(c)tau(q) > 1 /2; where omega(c) is the cyclotron frequency and tau(q) the quantum l ifetime. For those samples where tau(q) is low, we deduce that cyclotr on phonon emission plays no major role in energy loss, but the experim ents give no information in this regard when tau(q) is high. When the EEI method fails (i.e., omega(c)tau(q) > 1/2), then the nonoscillatory resistivity is found to be influenced by both tau(q) and the lattice temperature, and the electron temperature plays a lesser role, particu larly when tau(q) is very high.