The calculation of the effective g-factor in semiconductors is important because of the dependence of the Knight shift on this quantity. It has received particular attention in view of its anomalous characteristic in the relatively new semiconductors, namely the semimagnetic semiconductors or the diluted magnetic semiconductors ( dms) where the g-factors are found to be enhanced by two orders of magnitude with reference to the corresponding ordinary semiconductors.
The concept of 'effective spin Hamiltonian' and effective g-factors was first introduced by Laura M. Roth,who obtained an expression for this factor, considering the antisymmetric part of the g-tensor, noting that the symmetric part vanishes for a crystal with inversion symmetry. Yafet obtained an expression for the square of the effective g-factor, by considering explicitly the spin-orbit interaction. Misra and Kleinman derived an expression for the effective Pauli spin susceptibility as a function of the square of the effective g-factor. They have shown the equivalence of their results with that of Yafet. While the effective Pauli spin susceptibility depends on the square of the effective g-factor, the dependence of the Knight shift on the effectiveg-factor is linear ( Tripathi eta11981,1982) Thus, the sign of the g-factor is ascribed from the sign of the Knight shift.
Since the mean magnetic moments of the impurities are functions of temperature and change with magnetic field, in a dms the effective g-factor essentially depends on temperature, field and composition of the dms. Furthermore, the strong temperature and field dependence of the g-factor is believed to be responsible for the exotic temperature dependence of the quantum oscillation amplitude in the dms. In addition, most of the carrier-dependent magnetic properties of dms, which are important for spintronics, depend on effective g-factor.
References
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such an elaborate and beautiful explanation..
thak you sir Gouri S. Tripathi
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