Terahertz dielectric properties of single-crystal MgO

Modification of spintronic terahertz emitter performance through defect engineering

“…However, optical transmission, absorption and reflection effects in both the metallic and the MgO layer, as well as at the interfaces, have been taken into account by the transfer-matrix formalism. The general discussion for the spectra concerning remains valid, however their bandwidth is decreased due to the strong optical absorption in MgO occurring above 3 THz 31 .…”

“…There are no fit-parameters in this model besides the elastic scattering time and the transmission function, as described in the main text, as all material data is extracted from ab initio calculations.

Figure 10Absorption of the fs pulse through the Fe(12 nm)/Pt(6 nm) and Fe (2 nm)/Pt (3 nm) bilayers with incidence from the Pt side.

Figure 11( a ) Refractive and absorption index of MgO in the THz range. ( b ) Group and phase velocity in MgO depending on frequency using a Lorentz Oscillator model for the dielectric function 31 .

Figure 12Schematic of the material stacking involved in the optical calculations. The fs pulse (in red) is incident from the right side.

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“…( a ) Refractive and absorption index of MgO in the THz range. ( b ) Group and phase velocity in MgO depending on frequency using a Lorentz Oscillator model for the dielectric function 31 .…”

“…For a realistic description of the THz emission and propagation within the structure, we incorporate the material-dependent dielectric functions for the three main layers. The refractive index n and the absorption coefficient κ in MgO are calculated using fit data from experiments for a Lorentz oscillator model as presented in [31]. The results for MgO are shown in Fig.…”

“…Since the THz waves must propagate through a relatively thick layer of MgO, it is instructive to investigate the group-and phase velocity in this material. The resulting curves using the Lorentz Oscillator model [31] are shown in Fig. 11 b.…”