The magnetic state in the binary DyxGe1−x (x ≤ 0.02) alloy semiconductor

Diluted bulk magnetic alloy semiconductors DyxGe1−x (x ≤ 0.02) were prepared by a two-step fabrication procedure and studied experimentally by XRD, EDX and magnetic methods. The polycrystalline materials had the ccp (cubic closed-packed) structure of the host Germanium up to ≈2 at.% of Dysprosium. They exhibited different low-temperature and high-temperature behavior. Low-field dc magnetic susceptibility data showed sharp peaks and irreversibility between zero-field cooled and field-cooled states for x < 0.02. A stable antiferromagnetic phase with temperature of the antiferromagnetic to paramagnetic transition TN = 25 K was observed at x = 2 at.% of Dysprosium. The solubility range of the binary DyxGe1−x alloy system is limited to ∼2 at.% due to the large atomic radius of the solute. The low-temperature magnetic phase is characterized as spin-glass below 2 at.%. The magnetic relaxation and non-linear susceptibility χnl of Dy0.01Ge0.99 were analyzed, and the spin-glass phase was defined with the critical exponents of the phase transition β = 0.52 ± 0.10, γ = 2.85 ± 0.10 and δ = 6.49 ± 0.02. From the Curie-Weiss behavior of the susceptibility at high temperatures, we determined an average effective Dy-Dy exchange constant J1 = −6.90 K and effective magnetic moment per Dy ion µeff = 10.08 µB. The rare-earth Dy atoms behave as isolated in Ge matrix at high-temperatures.