A Study On The Theories For The Inverse Faraday Effect

The phenomena that the polarization of a polarized light beam is changed while traveling through some material are called Faraday effect. While the phenomena that a static magnetization generated in some materials by a passing circularly polarized light beam is called the inverse Faraday effect(IFE).Recently the IFE was observed in magnetically ordered materials and the non-thermal manipulation of magnetization with circularly polarized femtosecond laser was realized. All-optical magnetic recording was achieved. Original theory about the IFE was purely phenom-enological. Some microscopic theories were developed in plasmas, based on the model of free electrons. The IFE was considered to be resulted from the magnetic moments of circularly moving electrons driven by the circularly polarized light beam. Recent experimental progresses awake new interests in theories about the IFE. In magnetically ordered materials, electrons can not always be treated as free electrons and quantum effects are usually need to be considered. Hertel obtained an IFE magnetization by treating the electron gas as a continuous fluid, without details of the movement of individual electrons. The result is half of that of those circular motion theories. In this thesis, classical dynamics and quantum dynamics of an electron driven by a circularly polarized light beam are studied. At first the magnetic moment generated by classical motion is studied in details. The orbit of the electron is a solenoid of elliptic cross section, with axis parallel to its initial velocity. The generated magnetic moment depends on the direction of its initial velocity. Statistical average of the magnetic moments yield an magnetization, also half of that of those circular motion theories. Then quantum mechanics of an electron driven by a classical circularly polarized light beam is considered. We obtain analytical solutions to this non-stationary state problem by tricky transformation of variables and variables separations. The solutions consist of a discrete spectrum and a non-normalizable continuous spectra. On the classical orbit, the solutions show singular peaks.