Spin-Wave Resonance in Magnetic Semiconductor Thin Films - Experiment

Magnetic properties of polycrystalline thin films of chromium chalcogenide spinels (CdCr$\text{}_{2}$Se$\text{}_{4}$ lightly doped with indium and CdCr$\text{}_{2x}$In$\text{}_{2-2x}$Se$\text{}_{4}$) were studied. The ferromagnetic (FMR) and spin-wave resonance (SWR) techniques were used to investigate the temperature dependences of both the spin-wave stiffness constant D and the saturation magnetization M$\text{}_{s}$. The resonance spectra were recorded in the temperature range extending from 4.2 K to 300 K. The influence of indium concentration on M$\text{}_{s}$(T) and D(T) was studied. It was shown that lightly doped samples (In/Cd < 1% at.) exhibited the ferromagnetic ordering with M$\text{}_{s}$(T) and D(T) being the linear functions of T$\text{}^{3}$ $\text{}^{/}$ $\text{}^{2}$ and T$\text{}^{5}$ $\text{}^{/}$ $\text{}^{2}$, respectively. Higher concentration of indium produced the reentrant transition and spin-glass state of magnetic ordering in CdCr$\text{}_{2x}$In$\text{}_{2-2x}$Se$\text{}_{4}$. The temperature dependence of M$\text{}_{s}$ was also found from the FMR data for these two magnetic phases.