James G Vale | Searcharxiv

arXiv2018

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

(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.

cond-mat.str-el↗

arXiv2018

Evolution of the magnetic excitations in NaOsO$_3$ through its metal-insulator transition

The temperature dependence of the excitation spectrum in NaOsO$_{\text{3}}$ through its metal-to-insulator transition (MIT) at 410 K has been investigated using resonant inelastic X-ray scattering (RIXS) at the Os L$_{\text{3}}$ edge. High resolution ($ΔE \sim$ 56 meV) measurements show that the well-defined, low energy magnons in the insulating state weaken and dampen upon approaching the metallic state. Concomitantly, a broad continuum of excitations develops which is well described by the magnetic fluctuations of a nearly antiferromagnetic Fermi liquid. By revealing the continuous evolution of the magnetic quasiparticle spectrum as it changes its character from itinerant to localized, our results provide unprecedented insight into the nature of the MIT in NaOsO$_{\text{3}}$.

cond-mat.str-el↗