Candidate quantum spin ice in the pyrochlore Pr$_2$Hf$_2$O$_7$
  We report the low temperature magnetic properties of the pyrochlore Pr$_2$Hf$_2$O$_7$. Polycrystalline and single-crystal samples are investigated using time-of-flight neutron spectroscopy and macroscopic measurements, respectively. The crystal-field splitting produces a non-Kramers doublet ground state for Pr$^{3+}$, with Ising-like anisotropy. Below 0.5 K ferromagnetic correlations develop, which suggests that the system enters a spin ice-like state associated with the metamagnetic behavior observed at $\mu_0H_c\sim2.4$~T. In this regime, the development of a discrete inelastic excitation in the neutron spectra indicates the appearance of spin dynamics which are likely related to cooperative quantum fluctuations. 
Romain Sibille, Elsa Lhotel, Monica Ciomaga Hatnean, Geetha   Balakrishnan, Bj\"orn F\r{a}k, Nicolas Gauthier, Tom Fennell a...
cond-mat.str-el