Measurements of the Spin Susceptibility of 2D GaAs/AlGaAs Heterostructures into the Weak Interacting Region

We determine the spin susceptibility $\chi$ of a two- dimensional electron system in GaAs/AlGaAs heterostructures using the tilted-field method. The measurements are done on a very high quality heterojunction-insulated gate field-effect transistor (HIGFET) with a mobility as high as $1\times10^{7} cm^{2}/Vs$. We report the $\chi$ measurements on a single HIGFET specimen over a wide range of densities, from $1 \times10^ {10} cm^{-2}$ to $4\times10^{11}cm^{-2}$; deep into the weak interacting regime. The value of $\chi$ decreases monotonically with increasing density. In the low density region, $\chi$ follows an empirical formula proposed by Zhu et al. (\textit {Phys. Rev. Lett.}, \textbf{90}, 056805, 2003), but deviates from it as density increases beyond $6\times10^ {10} cm^{-2}$. After corrections for nonparabolicity of mass and g-factor, our $\chi$ measurements are very close to the most recent theoretical calculation (De Palo et al., cond- mat/0410145) over the whole density range.