Spin-splitting analysis of a two-dimensional electron gas in almost strain-free In0.89Ga0.11Sb/In0.88Al0.12Sb by magnetoresistance measurements

We investigated the spin-splitting in an almost strain-free In0.89Ga0.11Sb/In0.88Al0.12Sb two-dimensional electron gas (2DEG) by magnetoresi stance measurements at 1.5 K. A large effective gyromagnetic factor (g factor) vertical bar g*vertical bar=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 (mu=9.8 x 10(4) cm(2)/V s), a vanishing spin-splitting was also found around B similar to 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 Delta E-0D=3.5 meV was more than twice as large as the Rashba spin-splitting energy Delta E-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.