Thermodynamic properties of magnetically diluted dipolar spin ice

The alternating susceptibility of Ho(2)Ti(2)O(7) and Ho(1.9)La(0.1)Ti(2)O(7) and specific heat of Dy(2)Ti(2)O(7) and Dy(1.9)Y(0.1)Ti(2)O(7) are reported. Temperature dependence of the relaxation time obtained from susceptibility data of both Ho(2)Ti(2)O(7) and Ho(1.9)La(0.1)Ti(2)O(7) can be described assuming thermally activated relaxation. No indication of lambda-like anomaly is observed in specific heat of Dy(1.9)Y(0.1)Ti(2)O(7). The obtained results suggest that although 5% magnetic dilution reduces the relaxation time it is not sufficient to induce long-range ordering at least down to 100 mK. (C) 2003 Elsevier B.V. All rights reserved.