Figure 4

This figure compares the resonance peak locations in the reflected power measured in two different samples, plotted as f² vs B². Black circles and red triangles correspond to data measured in samples with density n_s ≈ 2.4 × 10¹¹ cm⁻² (data replotted from Fig. 3) and n_s ≈ 3.3 × 10¹¹ cm⁻², respectively. Effective mass ratios, m^*/m, are found from slopes of linear fit through the data, while plasmon frequencies, f_p, are found from the square root of the intercept. Inset: close-up of main graph near the origin.