Spin-splitting analysis of a two-dimensional electron gas in almost strain-free In_<0.89>Ga_<0.11>Sb/In_<0.88>Al_<0.12>Sb by magnetoresistance measurements

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We investigated the spin-splitting in an almost strain-free In_<0.89>Ga_<0.11>Sb/In_<0.88>Al_<0.12>Sb two-dimensional electron gas (2DEG) by magnetoresistance measurements at 1.5 K. A large effective gyromagnetic factor (g factor) |g^*|=33–34 was obtained by means of the coincidence method, which assumes an effective mass m^*=0.021m_0 at the Fermi energy. In spite of the large g factor and the high mobility (μ =9.8 × 10^4 cm^2 /V s), a vanishing spin-splitting was also found around B～0.8 T by analyzing the second derivative of the magnetoresistance. This effect originates from the interplay between the Rashba and Dresselhaus spin-orbit interactions, and we theoretically confirmed the fact that the Dresselhaus spin-splitting energy ΔE_<0D>=3.5 meV was more than twice as large as the Rashba spin-splitting energy ΔE_<0R>=1.5 meV. Moreover, we demonstrated that the theoretical curves of the normalized spin splitting, including the g factor and the spin-orbit interactions, were well fitted to the experimental points with the Dresselhaus spin-orbit interaction. Therefore, we concluded that the Dresselhaus spin-orbit interaction is dominant in our 2DEG in spite of its narrow band gap.
2008-05-15