Bulletin of the American Physical Society
APS March Meeting 2018
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session C24: 3D Frustrated Spin Systems: Pyrochlores and Spinels
2:30 PM–5:30 PM,
Monday, March 5, 2018
LACC Room: 403A
Sponsoring Units: GMAG DMP
Chair: Graeme Luke, McMaster Univ
Abstract: C24.00008 : Phase Competition in the Palmer-Chalker XY Pyrochlore Er2Pt2O7*
4:18 PM–4:30 PM
(National Institute of Materials Science)
(University of Winnipeg)
We report neutron scattering measurements on Er2Pt2O7, a new addition to the XY family of frustrated pyrochlore magnets. Symmetry analysis of our elastic scattering data shows that Er2Pt2O7 orders into the k = 0, Γ7 magnetic structure (the Palmer-Chalker state), at 0.38 K. This contrasts with its sister XY pyrochlore antiferromagnets Er2Ti2O7 and Er2Ge2O7, both of which order into Γ5 magnetic structures at much higher temperatures, 1.2 and 1.4 K, respectively. Below TN = 0.38 K, Er2Pt2O7 displays a gapped spin-wave spectrum with an intense, flat band of excitations at lower energy and a weak, diffusive band of excitations at higher energy. The flat band is well described by classical spin-wave calculations, but these calculations also predict sharp dispersive branches at higher energy, a striking discrepancy with the experimental data. This, in concert with the strong suppression of TN, is attributable to enhanced quantum fluctuations due to phase competition between the Γ7 and Γ5 states that border each other within a classically predicted phase diagram.
*The work was supported by the Natural Sciences and Engineering Research Council of Canada.
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