The electron density of states in terahertz-driven three-dimensional electron gases in quantizing magnetic fields

A detailed theoretical study of the density of states (DOS) is presented for free electrons in terahertz- (THz-) driven three-dimensional electron gases (3DEGs) in the presence of static magnetic fields. Applying the Green's function approach to a specific sample configuration where the electron - photon interactions can be included exactly, we have derived the steady-state DOS for electrons in a THz-driven 3DEG. The results obtained show that the presence of intense THz electromagnetic radiations will result in a reduction of the DOS in the low-energy regime in a 3DEG in quantizing magnetic fields. A photon-modified electron DOS will lead to the lifting of the Fermi level in a 3DEG system and, consequently, to the occupation of higher Landau levels at a fixed magnetic field. A more pronounced effect can be observed for relatively low-frequency and/or high-intensity radiations.