Magnetic Order in the Pyrochlore Iridates A2Ir2O7 (A = Y, Yb)

TL;DR

This study investigates magnetic ordering in pyrochlore iridates Y2Ir2O7 and Yb2Ir2O7 using multiple experimental techniques, revealing long-range magnetic order in Yb-227 and complex magnetic transitions in Y-227.

Contribution

It provides new experimental evidence of magnetic order and transitions in A2Ir2O7 iridates, highlighting the role of magnetic A-site ions and the similarity of ground states across different compounds.

Findings

Yb-227 exhibits long-range magnetic order below 130 K.

Y-227 shows magnetic transition at 150 K with a different magnetic state at 190 K.

Magnetic ground states are similar across insulating iridates regardless of A-site ion.

Abstract

We present results from muon spin relaxation/rotation, magnetization, neutron scattering and transport measurements on polycrystalline samples of the pyrochlore iridates Y2Ir2O7 (Y-227) and Yb2Ir2O7 (Yb-227). Well-defined spontaneous oscillations of the muon asymmetry are observed together with hysteretic behavior in magnetization below 130 K in Yb-227, indicative of commensurate long-range magnetic order. Similar oscillations are observed in Y-227 below 150 K; however the onset of hysteretic magnetization at T = 190 K indicates a transition to an intermediate state lacking long-range order as observed in Nd-227. Our results also show that insulating members of the iridate family have nearly identical magnetic ground states, and that the presence of magnetic A-site species does not play any significant role in altering the ground state properties.