Unpolarized quasielectrons and the spin polarization at filling fractions between 1/3 and 2/5

Abstract

We prove that for a hard core interaction the ground state spin polarization in the low Zeeman energy limit is given by $P=2/ν-5$ for filling fractions in the range $ 1/3 \leqν\leq 2/5 $. The same result holds for a Coulomb potential except for marginally small magnetic fields. At the magnetic fields $B<20T$ unpolarized quasielectrons can manifest themselves by a characteristic peak in the I-V characteristics for tunneling between two $ν=1/3$ ferromagnets.