Theory of "ferrisuperconductivity" in $U_{1-x}Th_xBe_{13}$

TL;DR

This paper develops a two-component Ginzburg-Landau theory to explain the complex phase diagram of U_{1-x}Th_xBe_{13}, predicting coexistence of superconducting states, charge density wave formation, and lattice distortions.

Contribution

It introduces a novel two-component Ginzburg-Landau model capturing the coexistence of staggered superconducting states and predicts associated lattice distortions and charge density wave phenomena.

Findings

Coexistence of two superconducting states at specific doping levels.

Prediction of charge density wave and lattice distortion below T_{c2}.

Explanation of experimental anomalies via impurity-mediated scattering.

Abstract

We construct a two component Ginzburg-Landau theory with coherent pair motion and incoherent quasiparticles for the phase diagram of $U_{1-x}Th_xBe_{13}$. The two staggered superconducting states live at the Brillouin zone center and the zone boundary, and coexist for temperatures $T\le T_{c2}$ at concentrations $x_{c1}\approx 0.02\le x \le x_{c2}\approx 0.04$. We predict below $T_{c2}$ appearance of a charge density wave (CDW) and Be-sublattice distortion. The distortion explains the $\mu$SR relaxation anomaly, and Th-impurity mediated scattering of ultrasound to CDW fluctuations explains the attenuation peak.