Multiple Superconducting Phases in Palladium Deuteride Induced by Nuclear-Spin Isotope Effect

TL;DR

This study reveals multiple superconducting phases in PdD$_{x}$ films, driven by nuclear-spin isotope effects, with distinct resistivity anomalies indicating complex phase behavior unlike PdH$_{x}$.

Contribution

It demonstrates the existence of multiple superconducting phases in palladium deuteride induced by nuclear-spin isotope effects, a novel finding in this material system.

Findings

Resistivity drops at ~1.7 K indicating superconductivity

Finite resistivity persists and vanishes at ~0.6 K

Multiple anomalies within the superconducting state

Abstract

We study the superconducting properties of high-quality PdD$_{x}$ films. The resistivity shows a sharp drop at $T$ $\sim$1.7 K, marking the superconducting transition. However, a finite resistivity persists and vanishes at $\sim$0.6 K. The temperature and magnetic-field dependences of the resistivity exhibit multiple anomalies within the superconducting state, revealing distinct superconducting phases. Such anomalies are absent in PdH$_{x}$ films. These results demonstrate a clear qualitative difference between the superconducting phase diagrams of PdD$_{x}$ and PdH$_{x}$, highlighting the role of nuclear-spin isotope effects.