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 μ=76 m2/V s show novel structures around ν=9/2 at low temperatures (50 mK≤T≤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).