Phase Competition in the Palmer-Chalker XY Pyrochlore Er2Pt2O7
A. M. Hallas, J. Gaudet, Nicholas Butch, Guangyong Xu, M. Tachibana, C. R. Wiebe, Graeme M. Luke, Bruce D. Gaulin
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 Er2Pt2Od7^ is the first XY pyrochlore to order into the κ = 0,Γ7 magnetic structure (the Palmer-Chalker state), below Τν = 0.38 K. This contrasts with its sister XY pyrochlore antiferromagnets Erd2^Ti2O7 and Er2Ge2O7, both of which order into Γ5 magnetic structures at much higher temperatures, with Τν=1.2 K and 1.4 K, respectively. Instead, in this temperature range, the magnetic heat capacity of Erd2^Pt2O7 contains a broad anomaly centered at Τ* = 1.5 K. Our inelastic neutron scattering measurements on Er2Pt2O7 reveal that this broad heat capacity anomaly sets the temperature scale for strong quasi-elastic spin fluctuations. Below Τν = 0.38 K, Er2Pt2O7 displays a gapped spin excitation spectrum with a narrow lower band of excitations, as often occurs in highly frustrated systems. This, in concert with the strong suppression of Τν, is attributable to phase competition between the Γd7^ and Γ5 states that border each other within a classically predicted phase diagram.
, Gaudet, J.
, Butch, N.
, Xu, G.
, Tachibana, M.
, Wiebe, C.
, Luke, G.
and Gaulin, B.
Phase Competition in the Palmer-Chalker XY Pyrochlore Er<sub>2</sub>Pt<sub>2</sub>O<sub>7</sub>, Physical Review Letters, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=924426
(Accessed December 8, 2023)