Electron-electron interaction in p-SiGe/Ge quantum wells

The temperature dependent magnetoresistance of high mobility p-SiGe/Ge quantum wells is studied with hole densities ranging from 1.7 to 5.9 × 1011 cm−2. At magnetic fields below the onset of quantum oscillations that reflect the high mobility values (up to 75000 cm2/Vs), we observe the clear signatures of electron-electron interaction. We compare our experiment with the theory of electron-electron interaction including the Zeeman band splitting. The observed magnetoresistance is well explained as a superposition of band structure induced positive magnetoresistance and the negative magntoresistance due to the electron-electron interaction effect.