Figure 1

Depolarized inelastic light scattering spectra (thick lines) and luminescence spectra (thin lines). The intensity of the luminescence has been rescaled to adjust a background intensity. (a) $\nu =1/3$. (b) $\nu \sim 0.386$. The inset shows the scattering geometry, where ${\omega }_S$ is the scattered photon energy.Reuse & Permissions

Figure 2

(a) Inelastic light scattering spectra at filling factor $\nu \lesssim 2/5$. The dots superimposed on the measured spectra are fits based on a broadened step density of states at the roton minimum in the SF mode dispersion (the spectra at $\nu =2/5$ has been scaled down by a factor of 2). The inset compares polarized (P) and depolarized (D) spectra. (b) Dispersion of SF modes at $\nu =2/5$ calculated by Mandal et al. [10]. The inset shows the scheme of spin-split Landau levels at $\nu =2/5$. Landau levels are labeled by quantum numbers and arrows that indicate orientation of spin. Composite fermions are shown as circles with two arrows that represent the two vortices attached to each electron.Reuse & Permissions

Figure 3

(a) Inelastic light scattering spectra at filling factors $\nu \gtrsim 1/3$. Light polarizations are as in Fig. 2. Vertical arrows show the peak assigned to the spin-flip mode. The inset shows the three lowest CF levels near $1/3$ and the transitions in SF modes and in charge density modes (CM). (b) Resonant inelastic light scattering spectra at $\nu =0.362$. Incident photon energies are given in meV. These spectra display the coexistence of ${\mathrm{S}\mathrm{F}}^{+}$ and ${\mathrm{S}\mathrm{F}}^{-}$ modes that occurs roughly in the middle of the filling factor range.Reuse & Permissions

Figure 4

Energies of low-lying modes as a function of perpendicular field $B$. (a) Spin modes. The dashed line is the $E_{\mathrm{S}\mathrm{F}}$ given by the variation of the CF cyclotron frequency as discussed in the text. The dotted line is a fit of the SW energy with $E_Z$ as described in the text. $p-1$ is the population of the second Landau level. (b) Rotons of charge density modes. The shaded area corresponds to the region where distinct modes originating from $2/5$ and $1/3$ coexist.Reuse & Permissions