Spin waves in double fractional quantum Hall systems

We have numerically obtained all the low-lying excitations for the double fractional quantum Hall (FQH) system by the exact diagonalization of finite systems. To interpret the results, the spin-wave (magnon) theory for the FQH system is rewritten for the spherical geometry to exploit the rotational symmetry. Remarkably, all the low-lying excitations in the single-layer system of spin 1 2 electrons at the Landau level filling v = 1 can be entirely interpreted in terms of multiplets of nearly-free magnons. We have also obtained the low-lying excitations in the double-layer system of spin-polarized electrons with layer separation d and inter-layer tunneling characterized by △_SAS to analyze single- and multi-(pseudo) magnon excitations.