Investigations of the effect of nonmagnetic Ca substitution for magnetic Dy on spin-freezing in Dy2Ti2O7

E-ISSN： 1361-648X|27|43|436001-436009

ISSN： 0953-8984

Source： Journal of Physics: Condensed Matter, Vol.27, Iss.43, 2015-11, pp. : 436001-436009

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Abstract

Physical properties of partially Ca substituted hole-doped Dy2Ti2O7 have been investigated by ac magnetic susceptibility &&dollar;{{chi}_{text{ac}}}(T)&dollar; ;, dc magnetic susceptibility &&dollar;chi (T)&dollar; ;, isothermal magnetization M(H) and heat capacity &&dollar;{{C}_{text{p}}}(T)&dollar; ; measurements on Dy1.8Ca0.2Ti2O7. The spin-ice system Dy2Ti2O7 exhibits a spin-glass type freezing behavior near 16 K. Our frequency dependent &&dollar;{{chi}_{text{ac}}}(T)&dollar; ; data of Dy1.8Ca0.2Ti2O7 show that the spin-freezing behavior is significantly influenced by Ca substitution. The effect of partial nonmagnetic Ca2+ substitution for magnetic Dy3+ is similar to the previous study on nonmagnetic isovalent Y3+ substituted Dy2−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% Ca2+ substitution for Dy3+ ions.