Novel structures near ν=9/2 in short-period unidirectional lateral superlattices

Unidirectional lateral superlattices with a period a = 92 nm fabricated from two-dimensional electron gas (2DEG) with mobility mu = 76 m(2)/V s show novel structures around v = 9/2 at low temperatures (50 mK less than or equal to T less than or equal to 350 mK). A shallow and broad dent with peaks on both sides appears when the direction of current is parallel to the direction of potential modulation, while a small peak emerges for the current direction parallel to the stripes of the grating. The observed phenomena resemble, albeit much smaller in magnitude, the anisotropic resistivity at half-filling of higher Landau levels recently observed in the plain 2DEGs with ultrahigh mobility and may be associated with the formation of charge density wave (CDW). (C) 2001 Elsevier Science Ltd. All rights reserved.