Wasp - Waisted loop and Spin frustration in Dy2-xEuxTi2O7 Pyrochlore

Abstract The Raman spectroscopy and AC and DC magnetization of Dy2−xEuxTi2O7 pyrochlore materials have been investigated. A systematic shift in all phonon modes with higher Eu content in Dy2−xEuxTi2O7 observed in Raman spectra confirms the successful substitution of Dy3+ ion by Eu3+ ions. High concentration of Eu induces the exchange interactions between atoms and alters the crystal-field interactions in Dy2−xEuxTi2O7. Rich Eu content samples (x = 1.5, 1.8 and 1.9) show the existence of wasp-waisted hysteresis loop which is explained on the basis of dipolar field, anisotropy exchange interaction and spin frustration present in the samples. Interestingly, AC susceptibility shows two single ion spin freezing transitions corresponding to Dy3+ and Eu3+ ions respectively in Eu rich samples only.