Distributed Hybridization Model for Quantum Critical Behavior in Magnetic Quasicrystals

TL;DR

This paper presents a distributed hybridization model explaining quantum critical behavior in magnetic quasicrystals containing ytterbium, reconciling observed magnetic susceptibility with mixed-valence features.

Contribution

It introduces a novel model expressing quasiperiodicity as a distribution of hybridization strengths, resolving contradictions in Yb quasicrystal properties.

Findings

Magnetic susceptibility shows power-law-like behavior.

Most Yb f electrons are in a renormalized paramagnetic state.

A small fraction of f moments remain unscreened.

Abstract

A quantum critical behavior of the magnetic susceptibility was observed in a quasicrystal containing ytterbium. At the same time, a mixed-valence feature of Yb ions was reported, which appears to be incompatible with the magnetic instability. We derive the magnetic susceptibility by expressing the quasiperiodicity as the distributed hybridization strength between Yb 4f and conduction electrons. Assuming a wide distribution of the hybridization strength, the most f electrons behave as renormalized paramagnetic states in the Kondo or mixed-valence regime, but a small number of f moments remain unscreened. As a result, the bulk magnetic susceptibility exhibits a nontrivial power-law-like behavior, while the average f-electron occupation is that of mixed-valence systems. This model thus resolves two contradictory properties of Yb quasicrystals.