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

The magnetoresistances of two-dimensional electron systems in strained sili con on a relaxed silicon-germanium buffer have been measured at low tempera tures (50 mK). Samples, with Hall mobilities up to 3.61 x 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 fi elds. It is argued that both of these phenomena can be explained by a stron g back-scattering of multiple edge modes which is suppressed at integer fil ling factors.