Emergent order in the spin-frustrated system DyxTb2-xTi2O7 studied by ac susceptibility measurements

TL;DR

This study investigates the complex magnetic behavior of Dy_xTb_{2-x}Ti_2O_7 through ac susceptibility measurements, revealing new peaks and effects related to crystal field levels and spin interactions across various compositions and magnetic fields.

Contribution

It provides new insights into the emergent magnetic order and the effects of doping and magnetic field on the spin dynamics in Dy-Tb titanate systems.

Findings

Discovery of a new susceptibility peak associated with Tb^{3+} at nonzero magnetic field.

T^* increases linearly with Dy doping in a wide composition range.

T^* is thermally driven with a large energy barrier, influenced by crystal field effects.

Abstract

We report the a.c. susceptibility study of Dy_xTb_{2-x}Ti_2O_7 with x in [0, 2]. In addition to the single-ion effect at Ts (single-ion effect peak temperature) corresponding to the Dy3+ spins as that in spin ice Dy_2Ti_2O_7 and a possible spin freezing peak at Tf (Tf < 3 K), a new peak associated with Tb^{3+} is observed in $\chi_{ac}(T)$ at nonzero magnetic field with a characteristic temperature T^* (Tf < T^* < Ts). T^* increases linearly with x in a wide composition range (0 < x < 1.5 at 5 kOe). Both application of a magnetic field and increasing doping with Dy3+ enhance T^*. The T^* peak is found to be thermally driven with an unusually large energy barrier as indicated from its frequency dependence. These effects are closely related to the crystal field levels, and the underlying mechanism remains to be understood.