Abstract
We develop the theory of the shift in the band edge caused by a strong exchange interaction between charge carrier spins and the spins of the localized magnetic electrons in ferromagnetic semiconductors.
The one-particle Green function is derived by using Matsubara's temperature Green functions, and then an infinite-order correction to the band edge due to the exchange interaction is determined from the poles of the Green function. With the aid of the temperature- and magnetic field-dependent spin polarization of the magnetic moments and the spin correlation functions, the band edge can be calculated as a function of temperature in various magnetic fields.
The calculated results are compared to experimental data in the cases of the ferromagnetic semiconductors EuO and Ga1-xMnxAs over a wide temperature range. For these materials the values 0.223 and 1.4 eV are evaluated for the exchange interaction parameter, respectively.
A new feature is found in the ferromagnetic region, as a result of the exceptionally strong exchange interaction in Ga1-xMnxAs, i.e., a blue-shift in the band edge with decreasing temperature or with increasing
The one-particle Green function is derived by using Matsubara's temperature Green functions, and then an infinite-order correction to the band edge due to the exchange interaction is determined from the poles of the Green function. With the aid of the temperature- and magnetic field-dependent spin polarization of the magnetic moments and the spin correlation functions, the band edge can be calculated as a function of temperature in various magnetic fields.
The calculated results are compared to experimental data in the cases of the ferromagnetic semiconductors EuO and Ga1-xMnxAs over a wide temperature range. For these materials the values 0.223 and 1.4 eV are evaluated for the exchange interaction parameter, respectively.
A new feature is found in the ferromagnetic region, as a result of the exceptionally strong exchange interaction in Ga1-xMnxAs, i.e., a blue-shift in the band edge with decreasing temperature or with increasing
| Original language | English |
|---|---|
| Pages (from-to) | 4491-4501 |
| Journal | Journal of Physics: Condensed Matter |
| Volume | 14 |
| Issue number | 17 |
| DOIs | |
| Publication status | Published - 2002 |
| MoE publication type | A1 Journal article-refereed |
Keywords
- magnetic semiconductors
- ferromagnetic materials
- band gap blue shift
- band shift