Putative magnetic quantum criticality in (Sr$_{\text{1-x}}$La$_{\text{x}}$)$_{\text{3}}$Ir$_{\text{2}}$O$_{\text{7}}$

TL;DR

This paper investigates magnetic quantum criticality in (Sr$_{1-x}$La$_x$)$_3$Ir$_2$O$_7$, analyzing resistivity and x-ray scattering data to suggest a crossover from quantum paramagnetic to quantum critical behavior near the insulator-metal transition.

Contribution

It provides evidence for magnetic quantum criticality in doped iridates and proposes a phase diagram illustrating the crossover behavior.

Findings

Resistivity scales linearly with temperature below Debye temperature.

X-ray scattering indicates a crossover from quantum paramagnetic to quantum critical behavior.

Extended doping region shows signs of quantum criticality.

Abstract

(Sr$_{1-x}$La$_x$)$_3$Ir$_2$O$_7$ undergoes a bulk insulator-to-metal transition (IMT) at $x \approx \mathrm{0.04}$. Through careful analysis of previously published data ($x=\mathrm{0.053, 0.061, 0.076}$), we find an extended region below the Debye temperature in which the resistivity appears to scale linearly with temperature. Meanwhile resonant (in)elastic x-ray scattering data ($x=\mathrm{0.065}$) suggest a possible crossover from quantum paramagnetic to quantum critical phenomenology between 100 and 200~K. We put this into context with other results, and propose a possible phase diagram as a function of doping.