Inter-edge-mode scattering in a high-mobility strained silicon two-dimensional electron system

The magnetoresistances of two-dimensional electron systems in strained silicon on a relaxed silicon-germanium buffer have been measured at low temperatures (50 mK). Samples, with Hall mobilities up to 3.61 × 10 5 cm 2 V -1 s -1 , have shown a marked asymmetry between adjacent Shubnikov-de Haas peaks and a prominent overshoot on the low-field side of the odd-filling-factor quantum Hall plateaux. This effect persisted to unusually small magnetic fields. It is argued that both of these phenomena can be explained by a strong back-scattering of multiple edge modes which is suppressed at integer filling factors.