title: Investigations of the effect of nonmagnetic Ca substitution for magnetic Dy on spin-freezing in Dy₂Ti₂O₇.
abstract: Physical properties of partially Ca substituted hole-doped Dy2Ti2O7 have been investigated by ac magnetic susceptibility χ(ac)(T), dc magnetic susceptibility χ(T), isothermal magnetization M(H) and heat capacity C(p)(T) measurements on Dy1.8Ca0.2Ti2O7. The spin-ice system Dy2Ti2O7 exhibits a spin-glass type freezing behavior near 16 K. Our frequency dependent χ(ac)(T) data of Dy1.8Ca0.2Ti2O7 show that the spin-freezing behavior is significantly influenced by Ca substitution. The effect of partial nonmagnetic Ca(2+) substitution for magnetic Dy(3+) is similar to the previous study on nonmagnetic isovalent Y(3+) substituted Dy(2-x)Y(x) Ti2O7 (for low levels of dilution), however the suppression of spin-freezing behavior is substantially stronger for Ca than Y. The Cole-Cole plot analysis reveals semicircular character and a single relaxation mode in Dy1.8Ca0.2Ti2O7 as for Dy2Ti2O7. No noticeable change in the insulating behavior of Dy2Ti2O7 results from the holes produced by 10% Ca(2+) substitution for Dy(3+) ions.
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner Platz 1, D-14109 Berlin, Germany.
authors.forename: V K
authors.initials: VK
authors.lastname: Anand
authors.forename: D A
authors.initials: DA
authors.lastname: Tennant
authors.forename: B
authors.initials: B
authors.lastname: Lake