Tilted magnetic field studies of spin- and valley-splittings in Si/Si 1 − xGe x heterostructures

Abstract

Magnetotransport measurements on the 2DEG of a Si/Si 1 − x Ge x heterostructure with an electron mobility of 32 m 2/Vs are presented. The coincidence method in a tilted magnetic field is used to determine the effective g factor. In the filling factor range 16 ≤ v ≤ 28 an almost constant effective g factor of g* = 3.39 is found. For lower filling factors, g* increases. Activation energy experiments at different tilting angles show that the size of the valley splitting depends only on the normal component of the magnetic field. Around filling factor v = 3 in a tilted field, an overshoot occurs in the Hall resistance, which is attributed to level crossings as a consequence of the exchange enhancement effects of spin- and valley-splitting.