Candidate quantum spin ice in the pyrochlorePr2Hf2O7

Abstract

Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher statement: © 2016 American Physical Society A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription. We report the low temperature magnetic properties of the pyrochlore Pr 2 Hf 2 O 7 . Polycrystalline and singlecrystal 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 μ 0 H c ∼ 2.4 T. In this regime, the development of a discrete inelastic excitation in the neutron spectra indicates the appearance of spin dynamics that are likely related to cooperative quantum fluctuations.

Single crystal growth, structure and magnetic properties of Pr2Hf2O7pyrochlore

“…The Pr 3+ effective moment is estimated to be µ eff = 2.51(1)µ B , a similar value to the one found in Pr 2 Zr 2 O 7 [27,39]. The calculated values of the CurieWeiss temperature θ W , and of the effective moment µ eff are in agreement with those determined by detailed investigations of the low temperature magnetic properties of our Pr 2 Hf 2 O 7 crystals [57]. We note the apparent discrepancy between the negative CurieWeiss temperature and the fact that the physics of Pr-based pyrochlores appears to be related to spin ice [27,57,59].…”

“…In Pr 2 Hf 2 O 7 the magnetization response is temperature dependent (see Figs. 6(a)-(f)), with the strongly anisotropic response only observed below about 10 K. Finally, we note the absence of evidence for a magnetization plateau developing in the M (H) curve when the field is applied along the [111] direction, as opposed to observations made at much lower temperature [57]. The discrepancy only arises from the difference in temperature, because ferromagnetic correlations only develop below 0.5 K in this system [57].…”

“…These results highlight the importance of investigating the crystal electric field (CEF) scheme in these systems. The crystal field splitting of Pr 3+ in Pr 2 Hf 2 O 7 was determined and the results are described elsewhere [57]. In Pr 2 Hf 2 O 7 the first excited level is about 9.2 meV ∼ 107 K above the ground state doublet, meaning that information concerning the magnetic interactions can be deduced from a Curie-Weiss analysis well below this temperature.…”

Antiferroquadrupolar correlations in the quantum spin ice candidatePr2Zr2O7

“…These results were interpreted as the evidence of quantum dynamics in a new class of spin ice system. Nevertheless, in Pr 2 Zr 2 O 7 and Pr 2 Hf 2 O 7 the Curie-Weiss temperature inferred from magnetic susceptibility is negative [21][22][23]25], thus indicating antiferromagnetic interactions, which is a priori not consistent with the spin ice picture. In addition, the fact that most of the neutron scattering signal in Pr 2 Zr 2 O 7 has an inelastic character calls for peculiar spin dynamics, different from conventional spin ice.…”

“…Recently, several theoretical studies [16][17][18] [24], and more recently Pr 2 Hf 2 O 7 [25] have shown that the Pr 3+ moment has a strong Ising character, described by a non-Kramers magnetic doublet. As in spin ice, no magnetic long-range ordering is observed down to dilution temperature, and magnetic specific heat shows a broad peak at about 2 K [21,22,[24][25][26][27], similar to what is observed in the classical spin ice Dy 2 Ti 2 O 7 .…”