Pulsed-field magnetization measurements in dilute magnetic semiconductors were made up to 55 T at 1.4 K in order to determine the nearest-neighbor antiferromagnetic exchange $J_{\mathrm{NN}}$ for ${\mathrm{Mn}}^{2+}$ pairs. For ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te (x=0.047), $J_{\mathrm{NN}/k_B=\mathrm{-}6.2\pm }$0.2 K. This ‖$J_{\mathrm{NN}\mathrm{\Vert }}$ was sufficiently small so that all five predicted ‘‘magnetization pair steps’’ due to pairs were observed with a pulsed-field magnet fabricated with a newly developed Cu/Nb metal-matrix microcomposite conductor. Two magnetization steps were observed in ${\mathrm{Zn}}_{1\mathrm{-}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Se (x=0.033), ${\mathrm{Zn}}_{1\mathrm{-}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te (x=0.031 and 0.040), and ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Se (x=0.049), from which we obtained $J_{\mathrm{NN}/k_B=\mathrm{-}12.2\pm }$0.3 K, -9.0±0.2 K, and -7.6±0.2 K, respectively.

• Received 24 January 1989

DOI:https://doi.org/10.1103/PhysRevB.39.11793