Magneto–Optical Kerr Spectroscopy of (Cd\({}_{\boldsymbol{3}}\)As\({}_{\boldsymbol{2}}\))\({}_{\boldsymbol{100-X}}\)(MnAs)\({}_{\boldsymbol{X}}\) Composites

Abstract

Composite films of (Cd\({}_{3}\)As\({}_{2}\))\({}_{100-X}\)(MnAs)\({}_{X}\) on silicon and sitall substrates with Mn concentration of 5.8–16.4 at \(\%\) were obtained by vacuum-thermal evaporation. The structural properties of the films were investigated by X-ray phase analysis and scanning electron microscopy. Magneto-optical properties were studied using the transverse Kerr effect (TKE) method in the energy range of 0.5–4.0 eV in magnetic fields up to 3 kOe at temperatures of 20–300 K. In the geometry of the transverse Kerr effect, the spectral, field, and temperature dependences of TKE were obtained. Analysis of experimental data showed that at Mn contents more than 12.9 at \(\%\) the films contain the \(\alpha^{\prime\prime}\)-phase of the topological Dirac semimetal Cd\({}_{3}\)As\({}_{2}\) in the form of large granules, as well as ferromagnetic MnAs granules. The Curie temperature of the films depends on their Mn content and is lower than that of bulk MnAs samples. At Mn contents in the film of 5.8 and 6.4 at \(\%\), no magneto-optical response was detected, indicating the formation of a superparamagnetic state or a spin glass state at low Mn concentrations. At an Mn content in the film of 9.9 at \(\%\), a significant change in magneto-optical spectra was observed, indicating the formation of MnAs nanoclusters and partial dissolution of Mn in the Cd\({}_{3}\)As\({}_{2}\) matrix.