Tadesse, Gebru (2006) The Study of Antiferromagnetic in Diluted Magnetic Semiconductor ”CDMNTE”. Masters thesis, Addis Ababa University.
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Abstract
Most of the semiconductor materials are diamagnetic by nature and therefore cannot take active part in the operation of the magneto-electronic devices. In order to enable them to be useful for such devices efforts have been made to develop diluted magnetic semiconductors (DMS) in which small quantity of magnetic ion is introduced in to normal semiconductors. The first known such DMS are II-VI and III-V semiconductors diluted with magnetic ions like Mn, Fe, Co, Ni, etc. Most of these DMS exhibit very high electron and hole mobility and thus useful for high speed electronic devices. CdMnTe systems with face centered cubic structure and long-range antiferromagnetic ordering is investigated with in the frame work of the Heisenberg model. The Hamiltonian includes exchange interactions with the nearest neighbors and Zeeman terms. Calculations are performed using Holstein-Primakoff transformation and Green’s function formalism. Temperature dependencies of the spin-wave specific heat and reduced magnetization are determined. In addition to these linear concentration dependence of Neel temperature is also predicted. The spin-wave energy shows T 4 temperature dependence, where as the predicted magnon part the heat capacity is proportional to T 3 which is similar to the Debye phonon heat capacity. The sublattice magnetization decreases quadratically with temperature in the low-temperature region. But the dependence of the Neel temperature on the manganese ion concentration is linear. All the findings are in broad agreement with experimental observations.
| Item Type: | Thesis (Masters) |
|---|---|
| Subjects: | Q Science > Q Science (General) Q Science > QC Physics |
| Divisions: | Africana |
| Depositing User: | Selom Ghislain |
| Date Deposited: | 13 Jul 2018 12:25 |
| Last Modified: | 13 Jul 2018 12:25 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/7376 |
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