Effect of Electron Spin Scattering To the Thermopower and Nernst Ettingsgauzen Effect in Magnetic Semiconductors
Abstract
Bu tez çalışmasında manyetik yarıiletkenlerde elektron-spin saçılmasının kinetik katsayılara katkısı araştırılmıştır. Bunun için Boltzman kinetik denkleminin çözümü, aynı zamanda birden fazla saçılma mekanizmasının var olduğu durum için genelleştirilmiş ve bu durumda kinetik tensörlerin genel ifadeleri bulunmuştur. Bu ifadeler dış manyetik alanın etki yaptığı durumda, termoelektromotor kuvveti ve Nernst Ettingsgauzen katsayısının bulunması için kullanılmıştır. Bulunmuş formüllerin incelenmesiyle, temel saçılma mekanizmalarına bağlı olarak spin saçılmasının değişik katkılarda bulunduğu tespit edilmiştir. Böyle ki; spin saçılmasının etkisiyle termoelektromotor kuvvetinin sıcaklığa bağlı davaranışı nonlineer karakter göstermiştir. Nernst Ettingsgauzen katsayısının ise işaret değiştirebileceği tesbit edilmiştir. Termoelektromotor kuvvetinin sıcaklığa bağlı nonlineer davranışı deney sonuçları ile karşılaştırılmış ve uyum sağladığı görülmüştür.
In this study, the contribution of the scattering of electron-spin in magnetic semiconductors to the kinetic coefficients has been investigated. For this aim, the solution of Boltzmann kinetic equation has been developed for the situation with many scattering mechanisms, and general relations of the kinetics tensors have been found. These expressions have been used to calculate the thermopower and Nernst Ettingsgauzen coefficient under the applied external magnetic field. By analyzing the present equations, it has been deduced that spin scattering has several contributions depending on the basic scattering mechanism. Thus, by the effect of the spin scattering the behavior of the thermopower as a function of temperature has shown the nonlinear character. It has also been concluded that the Nernst Ettingsgauzen coefficient can change the sign. The nonlinear behavior of the temperature-dependent thermopower has been compared with the related experimental data and it has been seen that the results are in good agreement.
In this study, the contribution of the scattering of electron-spin in magnetic semiconductors to the kinetic coefficients has been investigated. For this aim, the solution of Boltzmann kinetic equation has been developed for the situation with many scattering mechanisms, and general relations of the kinetics tensors have been found. These expressions have been used to calculate the thermopower and Nernst Ettingsgauzen coefficient under the applied external magnetic field. By analyzing the present equations, it has been deduced that spin scattering has several contributions depending on the basic scattering mechanism. Thus, by the effect of the spin scattering the behavior of the thermopower as a function of temperature has shown the nonlinear character. It has also been concluded that the Nernst Ettingsgauzen coefficient can change the sign. The nonlinear behavior of the temperature-dependent thermopower has been compared with the related experimental data and it has been seen that the results are in good agreement.
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Keywords
Fizik ve Fizik Mühendisliği, Boltzmann Denklemleri, Yarı İletkenlik, Physics and Physics Engineering, Boltzmann Equations, Semiconductivity
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