TITLE: Electron Self-Energy in a paramagnetic electron system

ABSTRACT:
 

In the many-body theory of the electron systems the spin polarization created in a magnetic field has been traditionally considewred as a small parameter. This picture is certainly true when the Zeeman splitting in a magnetic field 2g*B (2g* is the effective gyromagnetic factor) is much smaller than the other relevant energies in the problem. In dilute magnetic semiconductors (DMS) such as CdMnSe or GaMnAs however the interaction between the localised Mn spins and the free electrons generates a value for 2g* than can be as high as hundreds of times the band value.

In this situation the Zeeman splitting dominates the energy spectrum and the spin polarization can be close to one hundred per cent even in weak magnetic fields. Anticipated usage of these materials for spinotronics applications prompts a serious investigation of their properties specifically those of itinerant carrier system. The dielectric function x(q, w) of a paramagnetic 2D electron system is studied as a function of the degree of spin-polarization z. Our model explicitly incorporates the spin degree of freedom through the exchange x and correlations c local field corrections whose approximate expressions are used to determine the effective electron-electron interaction. The poles of x(q, w) are calculated and identified with the excitation frequency of the two orthogonal plasma modes associated with the collective charge and spin fluctuations. The electron self-energy is obtained as a parametric function of z.

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