Muon spin relaxation study of Hidden Ordering and Spin-glass-like transitions in Gd2Hf2O7

The ground state of Heisenberg pyrochlore antiferromagnet is the non-symmetry-breaking classical spin liquid with infinite degeneracy that can be lifted by perturbations like dipolar interactions and bond-disorder inducing long-range order and spin-glass state. The neutron diffraction study on Heisenberg pyrochlore Gd2Hf2O7 show evidence of bond-disorder, however no evidence for long-range magnetic ordering in specific heat and neutron diffraction measurements down to 0.07 K, but ac susceptibility reveals sharp peak (frequency-independent) near 0.68 K suggesting an ordering transition (hidden order), and a frequency-dependent spin-glass-like anomaly near 0.58 K. Because of the high sensitivity of muons to extremely small magnetic fields and suitability of SR for investigating the glassy spin-dynamics, µSR investigations of magnetic properties of Gd2Hf2O7 would be very informative. We propose to carry out a µSR study down to 0.05 K on Gd2Hf2O7 using the EMU spectrometer to uncover the nature of hidden transition.