Spin-splitting analysis of a two-dimensional electron gas in almost strain-freeIn0.89Ga0.11Sb/In0.88Al0.12Sbby magnetoresistance measurements

Abstract

We investigated the spin-splitting in an almost strain-free ${\text{In}}_{0.89}{\text{Ga}}_{0.11}{\text{Sb/In}}_{0.88}{\text{Al}}_{0.12}\text{Sb}$ two-dimensional electron gas (2DEG) by magnetoresistance measurements at 1.5 K. A large effective gyromagnetic factor ($g$ factor) $|{g}^{\ensuremath{\ast}}|=33--34$ was obtained by means of the coincidence method, which assumes an effective mass ${m}^{\ensuremath{\ast}}=0.021{m}_{0}$ at the Fermi energy. In spite of the large $g$ factor and the high mobility $(\ensuremath{\mu}=9.8\ifmmode\times\else\texttimes\fi{}{10}^{4}\text{ }{\text{cm}}^{2}/\text{V}\text{ }\text{s})$, a vanishing spin-splitting was also found around $B\ensuremath{\sim}0.8\text{ }\text{T}$ 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 $\ensuremath{\Delta}{E}_{0D}=3.5\text{ }\text{meV}$ was more than twice as large as the Rashba spin-splitting energy $\ensuremath{\Delta}{E}_{0R}=1.5\text{ }\text{meV}$. 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.