Abstract
We compare quantum Hall systems at filling factors to and , corresponding to the exact filling of two lowest electron or composite fermion (CF) Landau levels. The two fractional states are examples of CF liquids with spin dynamics. There is a close analogy between the ferromagnetic (spin polarization ) and paramagnetic incompressible ground states that occur in all three systems in the limits of large and small Zeeman spin splitting. However, the excitation spectra are different. At , we find spin domains at half-polarization , while antiferromagnetic order seems most favorable in the CF systems. The transition between and 1, as seen when, e.g., the magnetic field is tilted, is also studied by exact diagonalization in toroidal and spherical geometries. The essential role of an effective CF-CF interaction is discussed, and the experimentally observed incompressible half-polarized state is found in some models.
5 More- Received 1 October 2006
DOI:https://doi.org/10.1103/PhysRevB.75.045434
©2007 American Physical Society