Complexity in the medium-range order of gallium as a polyvalent liquid metal

TL;DR

This study reveals complex medium-range order in liquid gallium, showing overlapping atomic correlations that explain its anomalous thermodynamic and transport properties, challenging previous domain-based models.

Contribution

It uncovers two types of medium-range order in liquid gallium and links them to its unusual behaviors, providing new insights into semi-metallic liquids.

Findings

Identification of two types of medium-range order in liquid gallium

Overlapping and fluctuating atomic correlations explain anomalous properties

Challenges the domain-based view of liquid gallium's structure

Abstract

Simplicity in chemical composition does not always translate into simplicity in the structures and dynamics of liquids and solids. Some elementary liquid metals, such as gallium, show unusual behaviors in thermodynamic and transport properties as a result of their complex atomic structure and dynamics. In this work, we study the real-space atomic correlation function of liquid gallium by neutron scattering. In the pair-distribution function, there exist two kinds of medium-range order (MRO), characterized by oscillations beyond the first nearest neighbors. On the other hand, the first neighbor shell shows only one kind of bond. The two types of MRO are strongly overlapping in space and fluctuating in time. We propose that they are the basis for anomalous behavior of liquid gallium. This view challenges the current view that liquid gallium consists of fluctuating metallic and insulating domains. These findings shed new light on the interpretation of similar microscopic anomalies observed in other semi-metallic liquids.