Figure 5
(a) Time domain picosecond pulse response transmitted through 20 QL CrxSb2−xTe3 films with varying Cr concentrations x. The inset shows a magnified pulse response transmitted through the CrxSb2−xTe3 film and a reference transmission through a (0001) sapphire substrate at 4 K. (b) Plot of tan ϕ vs frequency. The solid lines represent the linear fit to each data set. The inset shows the scattering lifetime τ vs x. (c) The plots of mobility μ and carrier density p vs Curie temperature Tc deduced from the THz measurements (blue and pink curves) and Hall measurements (red and green curves), respectively. (d) Sheet carrier density, p1/3 x, as a function of Tc obtained from the THz measurements (blue curve) and Hall measurements (red curve). The inset shows carrier density p vs carrier concentration x. (e) THz conductance spectra of Cr0.76Sb1.24Te3 showing distinct features at ~1.9 THz referring to the optical phonon. (f) THz conductance at 1.3 THz as a function of T.
