The magnetic susceptibility and specific heat of the diluted magnetic semiconductor ${\mathrm{Zn}}_{1\mathrm{-}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Se have been measured in the temperature range 10 mK<T<40 K for 0.01≤x≤0.53. A paramagnetic–spin-glass transition was observed in the whole concentration range. The concentration dependence of the freezing temperature $T_f$ was found to be compatible with a radial dependence of the exchange interaction between manganese ions of the type J(R)∼$R^{\mathrm{-}6.8}$. Based on this observation, we calculated thermodynamic properties with the extended nearest-neighbor pair approximation. It appears that this approximation provides a good simultaneous description of the specific heat and high-field magnetization and reproduces Curie-Weiss temperature for parameters $J_0$/$k_B$=-13 K (nearest-neighbor interaction) and $J_i$(R)/$k_B$=-7/$R^{6.8}$ K (distant-neighbor interaction). A comparison is made with other dilute magnetic semiconductors, and the possible origin of the exchange mechanism is then discussed.

• Received 26 March 1987

DOI:https://doi.org/10.1103/PhysRevB.36.7013