Field-induced spin dynamics and crystal field effects in the frustrated pyrochlore Gd2Hf2O7

We present the structural and magnetic properties of the pyrochlore oxide Gd2Hf2O7 using x-ray diffraction, Raman spectroscopy, magnetization, AC susceptibility, and heat capacity measurements. Gd2Hf2O7 forms in a well-ordered cubic pyrochlore phase and exhibits the characteristic Raman-active modes, indicative of the stable local coordination. AC susceptibility measurements uncover a field-induced anomaly near 15 K, which is frequency-independent and shifts linearly with field, suggesting the presence of slow spin dynamics influenced by Zeeman splitting. Heat capacity data under applied fields reveal a Schottky-like anomaly that is well described by a multilevel Schottky model, consistent with crystal field splitting of the Gd3+ levels. These results point toward a cooperative spin response arising from the interplay of weak single-ion anisotropy and geometric frustration, positioning Gd2Hf2O7 as a model system for exploring field-tunable spin correlations in low-anisotropy pyrochlores.