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

TL;DR

This study investigates how substituting nonmagnetic Ca for magnetic Dy in Dy2Ti2O7 affects its spin-freezing behavior, revealing that Ca substitution significantly suppresses spin-glass freezing without altering the material's insulating properties.

Contribution

It provides new insights into the impact of nonmagnetic Ca substitution on spin-freezing in Dy2Ti2O7, showing a stronger suppression compared to Y substitution and analyzing the relaxation dynamics.

Findings

Ca substitution significantly suppresses spin-freezing behavior.

No change in insulating properties with Ca doping.

Single relaxation mode observed in Cole-Cole analysis.

Abstract

Physical properties of partially Ca substituted hole-doped Dy2Ti2O7 have been investigated by ac magnetic susceptibility \chi_ac(T), dc magnetic susceptibility \chi(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 \chi_ac(T) 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-xYxTi2O7 (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.