Spin dynamics in the new Pr-pyrochlore Pr2Pt2O7

Pr-based pyrochlores Pr2B2O7 (where B = Sn, Zr, Hf) have been considered as U(1) spin liquid, candidates because they do not show long-range magnetic order down to tens of mK. We have successfully synthesized polycrystalline samples of a new Pr-pyrochlore Pr2Pt2O7 using a high-pressure technique. Heat capacity measurements show a peak at ~150 mK attributed to either magnetic order, spin freezing, or a Schottky anomaly, while the ac susceptibility vs temperature data exhibit a frequency-dependence in both the real and imaginary components which is reminiscent of glassy freezing with some persistent dynamics. We propose to carry out muon spectroscopy experiments using MuSR to investigate the spin dynamics in this new Pr-pyrochlore Pr2Pt2O7.