Nonequilibrium low temperature phase in pyrochlore iridate Y$_2$Ir$_2$O$_7$: Possibility of glass-like dynamics

TL;DR

This study investigates the low-temperature phase of Y$_2$Ir$_2$O$_7$, revealing glass-like dynamics, absence of long-range magnetic order, and quantum interference effects in transport, highlighting complex frustrated magnetic behavior.

Contribution

It provides detailed experimental evidence of glass-like dynamics and non-traditional magnetic behavior in pyrochlore iridate Y$_2$Ir$_2$O$_7$, expanding understanding of frustrated magnetic systems.

Findings

No long-range ferromagnetic order below 160 K

Presence of glass-like relaxation and aging behavior

Negative magnetoresistance explained by quantum interference

Abstract

Geometrical frustration and spin-orbit coupling effect together play vital role to influence properties in pyrochlore based iridium oxides. Here we have investigated detailed structural, magnetic, thermodynamic and transport properties of pyrochlore iridate Y$_2$Ir$_2$O$_7$. Magnetization data show onset of magnetic irreversibility around temperature $T_{irr}$ $\sim$ 160 K, however, no sign of long-range type ferromagnetic ordering is observed below $T_{irr}$. Specific heat data show no visible anomaly across $T_{irr}$, and the analysis of data indicate sizable density of states across Fermi level. Temperature dependent x-ray diffraction measurements show no change in structural symmetry down to low temperature. The material, on the other hand, shows significant relaxation and aging behavior similar to glassy dynamics. The electronic charge transport in this highly insulating system is found to follow power law dependence with temperature. The material shows negative magnetoresistance which is explained with quantum interference effect.