Magnetotransport of $\nu$=3/2 composite fermions under periodic effective magnetic-field modulation
A. Endo, M. Kawamura, S. Katsumoto, and Y. Iye
Phys. Rev. B 63 113310 (2001)
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We report magntetotranport measurements around filling factor $\nu$=3/2 of two-dimensional electron gas under weak unidirectional periodic potential modulation. Composite fermions (CFs) at $\nu$=3/2, which are the electron-hole conjugate of $\nu$=1/2 CFs, show positive magnetoresistance (PMR) and oscillatory magnetoresistance --- commensurability oscillation (CO) --- for a modulation period of $a$=92 nm. Minima of the CO occur at the positions expected for commensurability with effective magnetic field modulation and are consistent with the field-dependent Fermi wave number $k_{\rm F}$ resulting from field-dependent density of the $\nu$=3/2 CFs. The positions are consistent with $k_{\rm F}$ for fully spin-polarized CFs, except for one dip which is better explained by fully spin-unpolarized $k_{\rm F}$, smaller by factor $\sqrt{2}$ than the spin-polarized counterpart. With introduction of in-plane magnetic field by tilting, the PMR shows unexpected asymmetry: it grows both in its magnitude and extent on the lower-field side, while it shrinks on the higher-field side.