In situ variation of the electron density via a metallic gate can control the disorder potentials in two-dimensional electron gases (2DEGs). This also influences the negative magnetoresistance at low magnetic fields, which is commonly observed in ultrahigh mobility 2DEGs. We investigate the temperature-dependent giant negative magnetoresistance (GNMR) as a function of the electron density for several temperatures and currents. Thereby, we find that the GNMR behavior depends decisively on the electron density. This observation is attributed to a changed disorder potential with electron density. In the case of higher electron densities, a nonlinear current dependency of the GNMR is observed, which could be described within the hydrodynamic regime.

中文翻译：

---

二维电子气中电子密度对巨负磁阻的影响

通过金属栅极的电子密度的原位变化可以控制二维电子气（2DEG）中的无序电势。这也会影响低磁场下的负磁阻，这在超高迁移率 2DEG 中常见。我们研究了温度依赖性巨负磁阻（GNMR）作为多种温度和电流下电子密度的函数。因此，我们发现 GNMR 行为决定性地取决于电子密度。这一观察结果归因于无序电势随电子密度的变化。在电子密度较高的情况下，观察到 GNMR 的非线性电流依赖性，这可以在流体动力学范围内进行描述。