X-ray Diffraction and Electrical Transport Imaging of Superconducting Superhydride (La,Y)H10

TL;DR

This study combines X-ray diffraction imaging and electrical transport measurements to explore the structural inhomogeneity and superconducting transitions in (La,Y)H10 superhydrides under high pressure, revealing the impact of phase distribution on superconductivity.

Contribution

It introduces a spatially resolved approach to correlate structural phases with superconducting properties in high-pressure hydrides, highlighting the influence of yttrium substitution.

Findings

Coexistence of cubic and hexagonal phases observed over 168-136 GPa.

Superconducting transitions at 244 K and 220 K linked to different phases.

Structural inhomogeneity affects the superconducting transition profiles.

Abstract

We report the synthesis and characterization of (La0.9Y0.1)H10 superhydrides exhibiting coexisting cubic Fm-3m and hexagonal P63/mmc clathrate phases observed over the pressure range from 168 GPa down to 136 GPa. Using synchrotron-based X-ray diffraction imaging (XDI) at the upgraded Advanced Photon Source (APS-U), we spatially resolved micron-scale distributions of these phases, revealing structural inhomogeneity across the sample. Four-probe DC resistance measurements confirmed superconductivity, with two distinct transitions: an onset at 244 K associated with the cubic phase and a second near 220 K linked to the hexagonal phase. Notably, resistance profiles collected from different current and voltage permutations showed variations in transition width and onset temperature that correlated with the spatial phase distribution mapped by XDI. These findings demonstrate a direct connection between local structural domains and superconducting behavior. Yttrium substitution is found to influence both the phase behavior and superconducting properties of LaH10-type clathrate hydrides. More broadly, this study highlights the utility of spatially correlating structural and electrical transport measurements in materials exhibiting heterogeneity under pressure, including hydride superconductors.