| Magnetization studies of several dilute magnetic materials are presented. The materials are: Zn{dollar}sb{lcub}1-x{rcub}{dollar}Fe{dollar}sb{lcub}x{rcub}{dollar}Se,Cu{dollar}sb2{dollar}Zn{dollar}sb{lcub}1-x{rcub}{dollar}Mn{dollar}sb{lcub}x{rcub}{dollar}Sn S{dollar}sb4{dollar}, and Mn{dollar}sb{lcub}1-x{rcub}{dollar}{dollar}rm Znsb{lcub}it x{rcub}Fsb2{dollar}.; The magnetization of cubic Zn{dollar}sb{lcub}1-x{rcub}{dollar}Fe{dollar}sb{lcub}x{rcub}{dollar}Se with {dollar}x{dollar} = 0.003 and 0.007 was measured at temperatures {dollar}2 le T sbsp{lcub}sim{rcub}{lcub}<{rcub} 50{dollar} K, in fields H parallel to the (100) and (111) directions. At low temperatures, M is anisotropic in high fields; the anisotropy disappears at low fields, and at all fields for high temperatures. At given values of T and {dollar}H{dollar} for which the anisotropy exists, {dollar}M{dollar} is greater if H {dollar}Vert{dollar} (100) than if H {dollar}Vert{dollar} (111). The maximum observed value of {dollar}Msb{lcub}lbrack 100rbrack{rcub}/Msb{lcub}lbrack 111rbrack{rcub}{dollar} is 1.19, at {dollar}H cong 150{dollar} kOe and T = 4.2 K. The results agree well with calculated values of {dollar}M{dollar} based on crystal field theory and the assumption that only isolated Fe{dollar}sp{lcub}++{rcub}{dollar} ions contribute to the magnetization. Slight differences between theory and experiment remain.; Magnetization measurements were performed for Cu{dollar}sb2{dollar}Zn{dollar}sb{lcub}1-x{rcub}{dollar}Mn{dollar}sb{lcub}x{rcub}{dollar}SnS{dollar}sb4{dollar}, dilute antiferromagnets with the tetragonal stannite structure, with {dollar}x = 1{dollar} and 0.88. Data were taken at temperatures {dollar}1.9 le T le 350{dollar} K in fields up to 50 kOe, and at {dollar}T = 0.6{dollar}, 1.4, and 4.2 K up to 300 kOe. They indicate that the material is an antiferromagnet with the easy axis along the {dollar}c{dollar} axis. For {dollar}x = 1, Tsb{lcub}N{rcub} = 8.8 pm 0.1{dollar} K, the spin flop occurs at 28 kOe, and the critical field is 245.5 {dollar}pm{dollar} 2 kOe. Mean field theory describes this sample well, and calculations show that the dipole-dipole interaction accounts for 61% of the anisotropy. The sample with {dollar}x = 0.88{dollar} showed the presence of a large number of bound magnetic polarons.; The dilute antiferromagnets Mn{dollar}sb{lcub}1-x{rcub}{dollar}Zn{dollar}sb{lcub}x{rcub}{dollar}F{dollar}sb2{dollar} exhibit a remanent magnetization {dollar}Msb{lcub}r{rcub}{dollar} along the easy axis at temperatures below {dollar}Tsb{lcub}N{rcub}{dollar}. This {dollar}Msb{lcub}r{rcub}{dollar} begins to saturate in axial fields as low as {dollar}Hsb{lcub}rm axial{rcub} sim 1{dollar} Oe. {dollar}Msb{lcub}r{rcub}{dollar} is a function of temperature and the axial field {dollar}Hsb{lcub}rm axial{rcub}(Tsb{lcub}N{rcub}{dollar}) present when cooling through {dollar}Tsb{lcub}N{rcub}{dollar}. Curves of {dollar}Msb{lcub}r{rcub}{dollar} vs. {dollar}T{dollar} for {dollar}x = 0.51{dollar} and {dollar}x = 0.25{dollar} have the same shape for all values of {dollar}Hsb{lcub}rm axial{rcub}(Tsb{lcub}N{rcub}{dollar}). Values of {dollar}betasb{lcub}r{rcub}{dollar}, the critical exponent governing {dollar}Msb{lcub}r{rcub}{dollar}, are obtained from curve fitting, and are between 0.35 and 0.40. Several theories are proposed to account for {dollar}Msb{lcub}r{rcub}{dollar}, but none is able to explain all observations. |
