Magnetotransport of nu=3/2 composite fermions under periodic effective magnetic-field modulation - art. no. 113310

We report magntetotranport measurements around a filling factor v = 3/2 of two-dimensional electron gas under weak unidirectional periodic potential m odulation. Composite fermions (CF's) at v = 3/2 which are the electron-hole conjugate of v = 1/2 CF's, show positive magnetoresistance (PMR) and oscil latory 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 consiste nt with the held-dependent Fermi wave number k(F) resulting from field-depe ndent density of the v = 3/2 CF's. The positions are consistent with k(F) f or fully spin-polarized CF's, except for one dip which is better explained by a fully spin-unpolarized k(F), smaller by factor root2 than its spin-pol arized counterpart. With the introduction of in-plane magnetic field by til ting the: PMR shows unexpected asymmetry: it grows both in its magnitude an d extent on the lower-field side, while it shrinks on the higher-field side .