Quantum Coherence and the Kondo Effect in the 2D Electron Gas of Magnetically Undoped AlGaN/GaN High-Electron-Mobility Transistor Heterostructures

The unusual observation of the Kondo effect in the two-dimensional electron gas (2DEG) of magnetically undoped AlGaN/GaN heterostructures is reported. The temperature-dependent zero-field resistivity data exhibits an upturn below 120 K, while the standard low-temperature weak localization and then weak antilocalization behaviour is revealed at T → 0. Magnetic transport investigations of the system are performed in the temperature range of 0.1–300 K and at magnetic fields up to 8 T, applied perpendicularly to the 2DEG plane. The experimental data are analyzed in terms of the multichannel Kondo model for d 0 magnetic materials and weak localization theory taking into account the spin-orbit interaction.