Electronic States of Al-Mg-Zn Quasicrystal and Its Approximant based on the First-Principles Calculations

TL;DR

This study uses first-principles calculations to analyze the electronic states of Al-Mg-Zn quasicrystals and their approximants, revealing differences in pseudogap structures that relate to their electrical resistivity behaviors.

Contribution

It provides detailed electronic structure insights of Al-Mg-Zn quasicrystals and approximants, highlighting the pseudogap features and their correlation with electrical properties.

Findings

1/1 approximant shows a wide pseudogap near the Fermi level.

2/1 approximant exhibits a narrow pseudogap at the Fermi level.

Electrical resistivity behavior correlates with pseudogap structures.

Abstract

First-principles calculations are performed to investigate the electronic states of 1/1 and 2/1 approximants with the composition Al$_{15}$Zn$_{40}$Mg$_{45}$ which is close to the quasicrystal (QC) Al$_{14.9}$Zn$_{41.0}$Mg$_{44.1}$ in which the superconductivity is recently discovered. The density of states for the 1/1 approximant shows a wide pseudogap structure near the Fermi level as commonly observed in various approximants of the QCs, whereas those for the 2/1 approximant do not show such a wide pseudogap. Instead of the wide pseudogap, the 2/1 approximant shows a remarkable narrow pseudogap at the Fermi level in contrast to the 1/1 approximant, which shows a shallow hump at the Fermi level within the wide pseudogap. This seems to be consistent with the experimental observation of the electrical resistivity, which increases with decreasing temperature from the room temperature down to around the superconducting transition temperature for the 2/1 approximant together with the QC, whereas it monotonically decreases for the 1/1 approximant.