Speaker
Description
Pyrochlore antiferromagnets (AFM) Gd2T2O7 (T: tetravalent metal elements) are prototypical materials for realizing classical spin liquid states. However, all of them have been observed to show long-range magnetic order [1-3]. Previous specific heat data of Gd2Hf2O7 show a tiny sharp peak on the top of a large broad maximum indicating a long-range AFM order [4]. However, our sample does not show that sharp peak in specific heat, but the ac susceptibility evidences an ordering transition followed by a spin-glass transition. Using neutron diffraction, we found that the sample has oxygen Frankel defects. The polarized neutron diffuse scattering pattern shows liquid-like scattering without any magnetic Bragg peaks. The subtle long-range order and re-entrant spin glass are attributed to bond disorder due to oxygen anion disorder.
[1] J. S. Gardner, et al., Reviews of Modern Physics 82, 53 (2010).
[2] X. Li et al., Phys. Rev. B 94, 214429 (2016).
[3] A. M. Hallas et al., Phys. Rev. B 91, 104417 (2015).
[4] M. D. Alice et al., J. Phys: Conden Matter 20, 235208 (2008).
