Structure and Magnetic Properties of the Pyrochlore Iridate Y2Ir2O7

TL;DR

This study investigates the structural and magnetic properties of Y2Ir2O7 using neutron diffraction and inelastic measurements, finding no evidence of magnetic long-range order or structural phase transitions between 3.4 K and 290 K.

Contribution

The paper provides detailed neutron diffraction data that set upper bounds on magnetic moments and confirms the absence of structural transitions in Y2Ir2O7 over a wide temperature range.

Findings

No structural phase transition observed from 3.4 K to 290 K.

No magnetic long-range order detected within measurement sensitivity.

Upper bounds on iridium magnetic moments are approximately 0.2 to 0.5 μB/Ir.

Abstract

Neutron powder diffraction and inelastic measurements were performed examining the 5d pyrochlore Y$_2$Ir$_2$O$_7$. Temperature dependent measurements were performed between 3.4 K and 290 K, spanning the magnetic transition at 155 K. No sign of any structural or disorder induced phase transition was observed over the entire temperature range. In addition, no sign of magnetic long-range order was observed to within the sensitivity of the instrumentation. These measurements do not rule out long range magnetic order, but the neutron powder diffraction structural refinements do put an upper bound for the ordered iridium moment of $\sim$ 0.2 $\mu_B /$Ir (for a magnetic structure with wave vector $Q \neq 0$) or $\sim$ 0.5 $\mu_B /$Ir (for Q = 0).