Transport-Coefficient Dependence of Current-Induced Cooling Effect in a Two-Dimensional Electron Gas

摘要

The dependence of the current-induced cooling effect on the electron mobility (mu)_(e) is explored for a two-dimensional electron gas (2DEG) subjected to a perpendicular magnetic field. We calculate the distributions of the electrochemical potentials and the temperatures under a magnetic field, fully taking account of thermoelectric and thermomagnetic phenomena. Whereas the electrochemical potential and the electric current remain qualitatively unchanged, the temperature distribution exhibits drastic mobility dependence. The lower-mobility system has cold and hot areas at opposite corners, which results from the heat current brought about by the Ettingshausen effect in the vicinity of the adiabatic boundaries. The cooling effect is intensified by an increase in (mu)_(e). Intriguingly, the cold and hot areas change places with each other as the mobility (mu)_(e) is further increased. This is because the heating current on the adiabatic edges due to the Righi-Leduc effect exceeds that due to the Ettingshausen effect in the opposite direction.