Magnetic measurements on quaternary manganese-based diluted magnetic semiconductors

We have studied the magnetic properties of Mn-based quaternary diluted magnetic semiconductors, Cd{dollar}sb{lcub}1-x-y{rcub}{dollar}Zn{dollar}sb{lcub}y{rcub}{dollar}Mn{dollar}sb{lcub}x{rcub}{dollar}Te, Cd{dollar}sb{lcub}1-x-y{rcub}{dollar}Mg{dollar}sb{lcub}y{rcub}{dollar}Mn{dollar}sb{lcub}x{rcub}{dollar}Te, Cd{dollar}sb{lcub}1-x{rcub}{dollar}Mn{dollar}sb{lcub}x{rcub}{dollar}Te{dollar}sb{lcub}1-y{rcub}{dollar}Se{dollar}sb{lcub}y{rcub}{dollar} and Zn{dollar}sb{lcub}1-x-y{rcub}{dollar}Mg{dollar}sb{lcub}y{rcub}{dollar}Mn{dollar}sb{lcub}x{rcub}{dollar}Te. The emphasis was on investigating the host dependence of the exchange interactions through the effective nearest neighbor exchange interaction, {dollar}Jsb1/ksb{lcub}B{rcub}{dollar}, and the spin glass transition temperature, {dollar}Tsb{lcub}f{rcub}{dollar}, at fixed low Mn concentration, x = 0.10, and different relative concentrations of the host constituents. The {dollar}Tsb{lcub}f{rcub}{dollar} was obtained from ac magnetic susceptibility measurements at 450 mK {dollar}<{dollar} T {dollar}<{dollar} 4 K and {dollar}Jsb1/ksb{lcub}B{rcub}{dollar} was obtained from a Curie-Weiss fit to the magnetization data measured at 4.5 K {dollar}<{dollar} T {dollar}<{dollar} 300 K for nominal x = 0.10 samples. From the study of the Cd{dollar}sb{lcub}1-x-y{rcub}{dollar}Zn{dollar}sb{lcub}y{rcub}{dollar}Mn{dollar}sb{lcub}x{rcub}{dollar}Te series we showed that {dollar}Tsb{lcub}f{rcub}{dollar} and {dollar}Jsb1/ksb{lcub}B{rcub}{dollar} varied linearly as a function of Zn concentration and the fractional change was 0.64 and 0.70 respectively, which within the error bars are identical. The observed host dependence of {dollar}Tsb{lcub}f{rcub}{dollar} contradicts the universality in {dollar}Tsb{lcub}f{rcub}{dollar} for wide-gap DMS systems that was suggested in earlier measurements. The Mg-based quaternary DMS are relatively new and they showed spin-glass transition at low temperatures. We did not observe any systematic variation of {dollar}Tsb{lcub}f{rcub}{dollar} and {dollar}Jsb1/ksb{lcub}B{rcub}{dollar} in the Cd{dollar}sb{lcub}1-x-y{rcub}{dollar}Mg{dollar}sb{lcub}y{rcub}{dollar}Mn{dollar}sb{lcub}x{rcub}{dollar}Te series at fixed x = 0.10 within our resolution. {dollar}Tsb{lcub}f{rcub}{dollar} was also measured for 0.2 {dollar}<{dollar} x {dollar}<{dollar} 0.60 for this series. Assuming a power law decay of the exchange interactions we plotted {dollar}Tsb{lcub}f{rcub}{dollar} vs. x on a log-log scale for three quaternary series. All the data points for the entire Mn concentration range could be represented by a single line for each of the three plots with the decay exponent, n = 6.36 {dollar}pm{dollar} 0.50, 6.69 {dollar}pm{dollar} 0.40 and 6.69 {dollar}pm{dollar} 0.70 for Cd{dollar}sb{lcub}1-x-y{rcub}{dollar}Zn{dollar}sb{lcub}y{rcub}{dollar}Mn{dollar}sb{lcub}x{rcub}{dollar}Te, Cd{dollar}sb{lcub}1-x-y{rcub}{dollar}Mg{dollar}sb{lcub}y{rcub}{dollar}Mn{dollar}sb{lcub}x{rcub}{dollar}Te and Cd{dollar}sb{lcub}1-x{rcub}{dollar}Mn{dollar}sb{lcub}x{rcub}{dollar}Te{dollar}sb{lcub}1-y{rcub}{dollar}Se{dollar}sb{lcub}y{rcub}{dollar} respectively, which is consistent with the value 6.8 observed earlier for Mn-based wide-gap quaternary DMS.